Systems and methods for controlling operation of a reduced pressure therapy system

ABSTRACT

Negative pressure wound therapy apparatuses and dressings, and systems and methods for operating such apparatuses for use with dressings are disclosed. In some embodiments, controlling the delivery of therapy can be based on monitoring and detecting various operating conditions. An apparatus can have a controller configured to monitor the duty cycle of a source of negative pressure and, based on the monitored duty cycle, determine whether a leak is present. The controller can be configured to provide an indication that a leak is present. For example, the controller can be configured to suspend and/or pause the delivery of therapy, and to restart the delivery of therapy due to a timeout, request from a user, etc. In addition, the controller can be configured to pause and/or restart the delivery of therapy upon a request from the user, such as in response to the user operating a switch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/287,959, filed on Nov. 2, 2011, which claims priority to U.S.Provisional Patent Application No. 61/511,950, filed on Jul. 26, 2011,and is a continuation-in-part of International Application No.PCT/GB2011/051748, entitled “PRESSURE CONTROL APPARATUS,” filed on Sep.16, 2011, which claims priority to Great Britain Patent Application1015656.0, filed on Sep. 20, 2010. The disclosures of all these priorapplications are hereby incorporated by references in their entireties.In addition, the disclosures of co-pending U.S. patent application Ser.No. 13/287,897 (Attorney Docket No. SMNPH.195A), entitled “REDUCEDPRESSURE THERAPY APPARATUSES AND METHODS OF USING SAME,” filed on Nov.2, 2011, and co-pending International Patent Application No.PCT/IB2011/002943 (Attorney Docket No. SMNPH.195WO), entitled “REDUCEDPRESSURE THERAPY APPARATUSES AND METHODS OF USING SAME,” filed on Nov.2, 2011, are hereby incorporated by reference in their entireties.

BACKGROUND Field of the Disclosure

Embodiments disclosed herein relate to methods and apparatuses fordressing and treating a wound with topical negative pressure (TNP)therapy. For example but without limitation, some embodiments disclosedherein relate to treating a wound with reduced pressure provided from apump kit. Although not required, some embodiments of the pump kit can besterile. As another non-limiting example, some embodiments disclosedherein relate to apparatuses and methods for controlling the operationof a TNP system.

Description of the Related Art

Many different types of wound dressings are known for aiding in thehealing process of a human or animal. These different types of wounddressings include many different types of materials and layers, forexample, gauze, pads, foam pads or multi-layer wound dressings. Topicalnegative pressure (“TNP”) therapy, sometimes referred to as vacuumassisted closure, negative pressure wound therapy, or reduced pressurewound therapy, is widely recognized as a beneficial mechanism forimproving the healing rate of a wound. Such therapy is applicable to abroad range of wounds such as incisional wounds, open wounds andabdominal wounds or the like.

TNP therapy assists in the closure and healing of wounds by reducingtissue oedema; encouraging blood flow; stimulating the formation ofgranulation tissue; removing excess exudates and may reduce bacterialload and thus, infection to the wound. Furthermore, TNP therapy permitsless outside disturbance of the wound and promotes more rapid healing.

SUMMARY OF SOME EMBODIMENTS

Some embodiments disclosed herein relate to a pump assembly for reducedpressure wound therapy, comprising a housing, a pump supported within orby the housing, a flow pathway through the pump assembly, and a one-wayflow valve in fluid communication with the pump and supported by thehousing. Some embodiments of the one-way flow valve can be configured tosubstantially prevent a flow of gas through the flow pathway in adirection of flow away from the pump. The pump can have a motor, aninlet and an outlet, a first valve supported by the pump and configuredto control a flow of a fluid through the inlet, and a second valvesupported by the pump and configured to control a flow of a fluidthrough the outlet.

Some embodiments disclosed herein relate to a pump assembly for reducedpressure wound therapy, comprising a housing, a pump supported within orby the housing, a one-way flow valve in fluid communication with thepump, and a flow pathway through the pump assembly. The one-way flowvalve can be configured to substantially prevent a flow of gas throughthe flow pathway in a direction of flow away from the pump. The pump cancomprise a motor, an inlet, and an outlet. In any of the pumpembodiments disclosed herein, though not required, the pump can alsohave a first valve configured to control a flow of a fluid through theinlet, and a second valve configured to control a flow of a fluidthrough the outlet. Some pump embodiments disclosed herein can useorifices or other features or components to control a flow or rate offlow of fluid through the pump.

Some embodiments disclosed herein relate to a negative pressure therapykit for reduced pressure wound therapy, comprising a pump assemblycomprising a housing, a pump supported within the housing, and acontroller supported within or by the housing, and at least one switchor button supported by the housing. As used throughout thisspecification, the phrase “some embodiments” or “in some embodiments” ismeant to refer to any embodiment described, illustrated, incorporated byreference, or otherwise disclosed herein. The at least one switch orbutton can be in communication with the controller and can be accessibleto a user so as to permit a user to control one or more modes ofoperation of the pump. In some embodiments, though not required, thenegative pressure therapy kit can comprise a dressing configured to forma substantially fluid tight seal over a wound, a conduit coupleable withthe dressing and the pump assembly and configured to provide asubstantially or completely enclosed fluid flow pathway from the pumpassembly to the dressing, and a first packaging element for packagingthe pump assembly, the one or more batteries, the dressing, and theconduit. In some embodiments, the controller can be configured tocontrol an operation of the pump and the valve. Some embodiments of thenegative pressure therapy kit can be configured such that the negativepressure therapy kit has been sterilized. The negative pressure therapykit can be sterilized such that at least an inside and an outside of thehousing, the at least one valve, the pump, the controller, and the atleast one switch or button have been sterilized. In some embodiments,the pump can have a pump motor, an inlet and an outlet, at least onevalve configured to control a flow of fluid through at least one of theinlet and the outlet, and a flow pathway through at least the inlet, theoutlet, and the at least one valve.

Some embodiments disclosed herein relate to reduced pressure treatmentof wounds with a reduced pressure pump. The pump embodiments disclosedherein are not required to be sterilized. However, sterilizing thereduced pressure pump before use and providing the pump and/or dressingor pump kit components in a sterile condition can permit the use of thepump in an operating room (also referred to as an operating theater) orany other location where sterility of the devices is required. Forexample and without limitation, some embodiments are directed to asterile pump kit comprising a sterile pump, a sterile dressing, and asterile conduit connectable to the dressing and the pump that can beused in an operating room.

Some embodiments disclosed herein relate to a negative pressure therapykit for reduced pressure wound therapy, comprising a pump having a flowrate of approximately 350 milliliters per minute or less, and a dressingcomprising a cover layer. The dressing can have a wound contact surfacethat is covered with a silicone based adhesive.

Some embodiments disclosed herein relate to a canisterless pump forreduced pressure wound therapy, comprising a housing, a flow pathwaythrough the pump, one or more valves in communication with the flowpathway, and a pump supported within or by the housing, wherein the pumpis canisterless. Some embodiments disclosed herein relate to acanisterless pump assembly for reduced pressure wound therapy,comprising a housing and a pump supported within or by the housing. Thepump can have a motor, an inlet and an outlet, a first valve supportedby the pump and configured to control a flow of a fluid through theinlet, and a second valve supported by the pump and configured tocontrol a flow of a fluid through the outlet. The pump or pump assemblycan be canisterless. Further, though not required for all embodimentsdisclosed herein, and the first and second valves can each have aleakage rate of from approximately 0.1 mL/min to approximately 10 mL/minat nominal working pressures and/or during nominal sterilizationpressures, or from 0.1 mL/min or less to 5 mL/min or more, or from 1mL/min or less to 3 mL/min or more, or between any two values in any ofthe foregoing ranges at nominal working pressures. In some embodiments,the leakage rate can be from approximately 0.4 mL/min to 0.7mL/min atnominal working pressures and/or during nominal sterilization pressures.

Some embodiments of the pump assembly can have a piezoelectric pump,such as without limitation the piezoelectric pump disclosed in U.S. Pat.No. 7,550,034 and/or US 2011/186765. Some piezoelectric pumps can haveorifices to perform the valve functions such that, when the pump is atrest, the flow rate through the pump can be as high as 200 mL/min.Therefore, in some embodiments, where the pump rate can be as high asapproximately 300 mL/min or 320 mL/min or otherwise, the first andsecond valves (which can be orifices) can each have a leakage rate of upto approximately 200 mL/min.

Some embodiments disclosed herein relate to a sterile pump kit,comprising any of the pump embodiments disclosed herein, a dressing, aconduit coupleable with the dressing and the sterile pump and configuredto provide a fluid pathway of reduced pressure to the dressing, one ormore batteries, and a first packaging element and a second packagingelement configured to be removably coupled with the first packagingelement. In some embodiments, at least one of the first and secondpackaging elements can have recesses for receiving the sterile pump, adressing, a conduit coupleable with the dressing and the sterile pumpand configured to provide a fluid pathway of reduced pressure to thedressing. The sterile pump kit can be been sterilized after the pump,the dressing, the conduit, and the one or more batteries have beensupported inside at least one of the first packaging element and thesecond packaging element.

Some embodiments disclosed herein relate to a method for initiatingtreatment of a wound in an operating room, comprising applying a steriledressing over a wound so as to create a substantially fluid tight sealover the wound, coupling a sterile pump to dressing via a sterileconduit, and reducing a level of pressure between the dressing and thewound in an operating room by activating the pump in the operating room.

Some embodiments disclosed herein relate to apparatuses and methods forcontrolling operation of a negative pressure wound therapy system. Inparticular, but without limitation, embodiments disclosed herein relateto negative pressure therapy apparatuses and dressings, and methods andalgorithms for operating such negative pressure therapy systems. In someembodiments, though not required, an apparatus can comprise a dressingconfigured to be placed over a wound and to create a substantially fluidimpermeable seal over the wound. An apparatus can comprise a source ofnegative pressure configured to be coupled to the dressing. Theapparatus can further comprise a controller configured to activate thesource of negative pressure, monitor a duty cycle of the source ofnegative pressure, and determine if the duty cycle exceeds a duty cyclethreshold. In some embodiments, the controller can be configured tomonitor a plurality of duty cycles of the source of negative pressureover a plurality of consecutive and equal time durations, and determineif a duty cycle of the plurality of duty cycles exceeds a duty cyclethreshold. The duty cycle can reflect an amount of time the source ofnegative pressure is active during a period of time or during a timeduration of the plurality of consecutive and equal time durations

In some embodiments, the controller can be configured to determine if anumber of duty cycles exceed the duty cycles threshold and if thatnumber exceeds an overload threshold. In some embodiments, thecontroller can be configured to determine if a set of duty cycles fromthe plurality of duty cycles exceeds a duty cycle threshold anddetermine if the number of duty cycles in the set exceeds an overloadthreshold. The controller can be configured to determine if the numberof duty cycles that exceeds the duty cycle threshold are consecutive. Insome embodiments, the overload threshold can comprise 30 duty cycles,the period of time or time duration can comprise one minute, and/or theduty cycle threshold can comprise 9%. In some embodiments, thecontroller can be configured to continuously monitor the duty cycle orthe plurality of duty cycles.

Some embodiments of the apparatus comprise a switch configured to pausethe source of negative pressure for a period of time and the controllercan be configured to restart the source of negative pressure uponexpiration of the period of time. The period of time can be variable. Insome embodiments, the apparatus can be enclosed in a housing comprisingan exterior surface and the switch comprises a button located on theexterior surface of the housing.

Some embodiments of the apparatus comprise a controller configured toprovide an indication of an operating condition. The operation conditioncan comprise determining that the duty cycle exceeds the duty cyclethreshold and the indication can comprise deactivating the source ofnegative pressure to indicate a leak in the seal. In some embodiments,the operating condition comprises whether the source of negativepressure is paused and the controller can be configured to provide afirst indication when the source of negative pressure is active and asecond indication when the source of negative pressure is paused,wherein the second indication is different from the first indication.

In some embodiments, the controller can be configured to activate thesource of negative pressure to attempt to generate a desired negativepressure level under the dressing and if upon expiration of a first timeinterval, a pressure level under the dressing has not reached thedesired negative pressure level, the controller can deactivate thesource of negative pressure for a second time interval. Upon expirationof the second time interval, the controller can activate the source ofnegative pressure to attempt to generate the desired negative pressurelevel under the dressing. The controller can be configured to vary thesecond time interval based on a number of times the pressure level underthe dressing has not reached the desired negative pressure level. Forexample, the controller can be configured to double the second timeinterval provided that a resulting value does not exceed a secondinterval threshold. The apparatus can comprise a sensor configured tosense pressure under the dressing and to communicate the sensed pressureto the controller.

In some embodiments, the controller can be configured to deactivate thesource of negative pressure when the pressure level under the dressinghas reached the desired negative pressure level and activate the sourceof negative pressure when the pressure level under the dressing risesabove a negative pressure threshold, wherein the desired negativepressure level corresponds to a pressure that is more negative than thenegative pressure threshold.

In some embodiments, the source of negative pressure can be operated bypositioning a dressing over a wound to create a substantially fluidimpermeable seal over the wound, delivering negative pressure to thedressing from the source of negative pressure, monitoring a duty cycleof the source of negative pressure, and providing an indication if theduty cycle is determined to exceed a duty cycle threshold. The dutycycle can reflect an amount of time the source of negative pressure isactive during a period of time, such as once per minute.

Some embodiments of the apparatus can be configured to monitor a totalelapsed time since an initial activation and disable the activation ofthe source of negative pressure when the total elapsed time reaches alifetime threshold. The life time threshold can comprise, for example, 7days.

In some embodiments, the apparatus for applying negative pressure to awound comprises a dressing configured to be placed over the wound and tocreate a substantially fluid impermeable seal over the wound, a sourceof negative pressure configured to be coupled to the dressing, and acontroller configured to activate the source of negative pressure,monitor a duty cycle of the source of negative pressure, and provide anindication if the duty cycle exceeds a duty cycle threshold.

In some embodiments, the apparatus comprises a dressing configured to beplaced over the wound and to create a substantially fluid impermeableseal over a wound, and a pump is configured to be coupled to thedressing, a switch configured to pause the pump for a period of time,and a controller configured to restart the pump upon expiration of theperiod of time. The period of time can be variable. Some embodiments ofthe apparatus comprise a miniature diaphragm pump operated by a motor ora miniature diaphragm pump operated by a piezoelectric transducer. Insome embodiments, the pump can comprise a miniature piston pump and aminiature diaphragm pump.

Some embodiments disclose a method of operating a source of negativepressure (e.g., a negative pressure pump), the method comprisingpositioning a dressing over a wound to create a substantially fluidimpermeable seal over the wound, delivering negative pressure to thedressing from the pump, pausing the pump for a period of time, andrestarting the pump upon expiration of the period of time. The period oftime can be variable.

In some embodiments, a negative pressure pump can be operated bypositioning a dressing over a wound to create a substantially fluidimpermeable seal over the wound, aspirating fluid from the wound usingthe negative pressure pump, measuring a level of activity of the pump,comparing the level of activity of the pump to a threshold, andproviding an indication if the level of activity exceeds the threshold.Measuring the level of activity can comprise determining a duty cycle ofthe pump, determining a flow rate of the fluid aspirated from the wound(e.g., by using a flow meter), measuring a rate of change of pressureunder the dressing using a pressure sensor, etc. or any combinationthereof.

Some embodiments disclose a method for operating a negative pressurepump, comprising positioning a dressing over a wound to create asubstantially fluid impermeable seal over the wound, delivering negativepressure to the dressing from the pump to draw pressure under thedressing toward a first negative pressure set point, activating the pumpto draw pressure under the dressing toward the first set point if thelevel of negative pressure under the dressing rises above a secondnegative pressure set point, monitoring an amount of time the pump hasbeen operating, and providing an indication if the amount of timeexceeds a predetermined amount of time. The method can further comprisedetermining the amount of time that the pump has been operating over aperiod of time and providing the indication if the amount of timeexceeds 9% of the period of time. In some embodiments, providing theindication further comprises determining the amount of time that thepump has been operating over a period of time. In some embodiments,providing the indication further comprises activating an alarm.

In some embodiments, the apparatus can be configured to activate asource of negative pressure to draw a pressure under a negative pressurewound therapy dressing to a desired negative pressure value, such as avalue between a first set point and a second set point or approximatelyequal to the second set point value. The level of pressure under thedressing can be measured. The apparatus can be configured to activatethe source of negative pressure to draw the pressure under the dressingtoward a second desired negative pressure level (e.g., the second setpoint value) if pressure under the dressing decays above a threshold(e.g., decays to the first set point value). The amount of time that thesource of negative pressure has been operating, for example,continuously, can be monitored. The operation of the source of negativepressure can be paused or discontinued if the source of negativepressure has been operating for a predetermined amount of time withoutestablishing approximately the second desired negative pressure levelunder the dressing (e.g., the second set point value).

Some embodiments disclose a method of operating a source of negativepressure, comprising positioning a dressing over a wound to create asubstantially fluid impermeable seal over the wound and deliveringnegative pressure to the dressing from the source of negative pressure.Delivering negative pressure to the dressing from the source of negativepressure comprises activating the source of negative pressure to attemptto generate a desired negative pressure level under the dressing andupdating a first count of activations; if upon expiration of a firsttime interval, negative pressure under the dressing has not reached thedesired negative pressure level, deactivating the source of negativepressure for a second time interval, provided that the first count ofactivations is less than a first retry threshold; if the first count ofactivations is not less than the first retry threshold, deactivating thesource of negative pressure for a third time interval, resetting thefirst count of activations, and, upon expiration of the third timeinterval, activating the source of negative pressure to attempt togenerate the desired negative pressure level under the dressing;activating the source of negative pressure upon expiration of the secondtime interval to attempt to generate the desired negative pressure levelunder the dressing and updating the first count of activations;deactivating the source of negative pressure when the negative pressureunder the dressing has reached the desired negative pressure level,resetting the first count of activations, and monitoring negativepressure under the dressing; when negative pressure under the dressingrises above a negative pressure threshold, activating the source ofnegative pressure and updating a second count of activations, whereinthe desired negative pressure level corresponds to a pressure that ismore negative than the negative pressure threshold; if before expirationof a fourth time interval negative pressure under the dressing hasreached the desired negative pressure level, deactivating the source ofnegative pressure, monitoring negative pressure under the dressing, andresetting the second count of activations; if upon expiration of thefourth time interval negative pressure under the dressing has notreached the desired negative pressure level, deactivating the source ofnegative pressure for the second time interval, provided that the secondcount of activations is less than a second retry threshold; if thesecond count of activations is not less that the second retry threshold,deactivating the source of negative pressure for the third timeinterval, resetting the second count of activations, and, uponexpiration of the third time interval, activating the source of negativepressure to attempt to generate the desired negative pressure levelunder the dressing and updating the first count of activations;continuously monitoring a duty cycle of the source of negative pressure;tracking a number of duty cycles that exceed a duty cycle threshold; anddeactivating the source of negative pressure for a duration of the thirdtime interval when the number of duty cycles that exceed the duty cyclethreshold exceeds an overload threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described hereinafter,by way of example only, with reference to the accompanying drawings inwhich:

FIG. 1 illustrates an embodiment of a reduced pressure wound therapyapparatus comprising a pump, a dressing, and a conduit.

FIGS. 2A-2F are various views of the embodiment of the pump illustratedin FIG. 1.

FIG. 3A illustrates an embodiment of a wound dressing kit comprising adressing, a pump, a conduit, two batteries, and one or more sealingstrips supported in a first packaging element.

FIG. 3B is a bottom isometric view of the embodiment of the wounddressing kit of FIG. 3A.

FIG. 3C is an exploded view of the embodiment of the wound dressing kitof FIG. 3A.

FIG. 4A is a first exploded view of the embodiment of the pump of FIG.1.

FIG. 4B is a second exploded view of the embodiment of the pump of FIG.1.

FIGS. 5A and 5B are first and second views of the first housing member.

FIGS. 6A and 6B are first and second views of the second housing member.

FIGS. 7A-7D illustrate the use of an embodiment of a TNP wound treatmentsystem being used to treat a wound site on a patient.

FIGS. 8A-20H are top isometric, bottom isometric, top plane, bottomplane, front, back, first side, and second side views, respectively, ofembodiments of packaging elements that can be used with any of theembodiments of the wound dressing apparatuses disclosed herein,including a variety of differently sized wound dressing apparatuses.

FIG. 21 illustrates a pump assembly according to some embodiments.

FIG. 22 illustrates a cross-sectional view showing the interior of apump assembly according to some embodiments.

FIG. 23 illustrates a system schematic of a pump assembly according tosome embodiments.

FIG. 24 illustrates an electrical component schematic of a pump assemblyaccording to some embodiments.

FIG. 25 illustrates a top level state diagram of operation of a pumpassembly according to some embodiments.

FIG. 26 illustrates an operational state diagram of operation of a pumpassembly according to some embodiments.

FIG. 27 illustrates another state diagram of operation of a pumpassembly according to some embodiments.

FIG. 28 illustrates a graph depicting a duty cycle determination for apump assembly according to some embodiments.

FIG. 29 illustrates operation of a pump assembly in presence of a lowleak according to some embodiments.

FIG. 30 illustrates operation of a pump assembly in presence of a highleak according to some embodiments.

FIG. 31 illustrates operation of a pump assembly in presence of a veryhigh leak according to some embodiments.

FIG. 32 illustrates operation of a pump assembly in presence of anextremely high leak according to some embodiments.

In the drawings like reference numerals refer to like parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments disclosed herein relate to apparatuses and methods oftreating a wound with reduced pressure. As is used herein, reduced ornegative pressure levels, such as −X mmHg, represent pressure levelsthat are below standard atmospheric pressure, which corresponds to 760mmHg (or 1 atm, 29.93 inHg, 101.325 kPa, 14.696 psi, etc.). Accordingly,a negative pressure value of −X mmHg reflects absolute pressure that isX mmHg below 760 mmHg or, in other words, an absolute pressure of(760−X) mmHg. In addition, negative pressure that is “less” or “smaller”than X mmHg corresponds to pressure that is closer to atmosphericpressure (e.g., −40 mmHg is less than −60 mmHg). Negative pressure thatis “more” or “greater” than −X mmHg corresponds to pressure that isfurther from atmospheric pressure (e.g., −80 mmHg is more than −60mmHg).

Some of the embodiments comprise a pump and/or a pump and dressing kit.Some embodiments are directed to a pump and/or pump and dressing kitthat have been sterilized before delivery to the hospital, operatingroom or theatre, or to the medical practitioner using such devices suchthat the sterile pump and/or a sterile pump/dressing kit can be appliedimmediately following the surgical or operating procedures. Oneadvantage of this is that the surgeon can release the patient from theoperating room knowing that the reduced pressure pump is operating andthat the reduced pressure therapy has been started at the earliest pointin time possible. A further advantage of applying the dressing kitimmediately following the surgical or other procedure is that doing socan reduce the chance of infection by eliminating a subsequent dressingchange that may otherwise be required in the ward. In other words, forthose patients where a dressing (but not a pump) is applied in theoperating theatre and then a problem is found thereafter, such as a leakor other issue with the dressing, if the dressing is required to beremoved to be repositioned, replaced, or otherwise after the patient isreleased from the operating theater, the patient's wound may be exposedto infection risk when the dressing is repositioned, replaced, orotherwise outside of the operating theater. However, with theembodiments disclosed herein, if the pump is applied and tested whilethe patient is in the operating theater, any issues with the dressingthat may require the dressing to be removed, repositioned, or otherwise,can be handled in the sterile operating room environment, therebysignificantly reducing or eliminating the risk of exposure to pathogens,bacteria, or other contaminants. Further, it is generally not possiblefor a hospital to sterilize a traditional pump once it has been receivedby the hospital, and therefore the hospital may resort to bagging thepumps in sterile bags but risk compromising the operating room sterilefield with this approach, particularly once the device is turned on andpathogens, bacteria, or other contaminants that may be inside the pumpare release due to the operation of the pump.

In some embodiments, the pump can be configured to be amenable to gassterilization, having features, components, and other characteristicsthat make the pump amenable to full sterilization gas exposure andpenetration throughout the components of the pump. For example, withoutlimitation, one or more pump valves have been selected or configured topermit a sufficient flow of sterilization gas therethrough such that theentire fluid pathway within the pump can be exposed to the sterilizationgas. As will be explained in greater detail below, in some embodiments,the pump can have other components, such as without limitation,strategically positioned one way flow valves, to complement the othervalves within the pump, which can improve the efficiency of the pump byreducing leakage through the flow pathway within the pump assembly.

Additionally, where provided, the sterile pump/dressing kit can also bedesigned and configured to be amenable to gas sterilization. Asdescribed below, the sterile pump/dressing kit can be configured suchthat all of the components comprising the sterile pump/dressing kit,including the pump assembly, are packaged together in at least a firstpackaging element before sterilization, permitting all of the componentsto be sterilized together. Furthermore, as will be described, thecomponents comprising the sterile pump/dressing kit can be arranged inthe packaging such that at least some of the components can be removedin a predefined order, making it easier for the surgeon or medicalpractitioner to assemble and apply the dressing to the patient.

There are a number of benefits to being able to begin treatment of awound in the operating theater, including without limitation providing asubstantially sealed barrier over the wound while the wound is in asterile condition and environment that will inhibit or prevent bacteriaor other contaminants from getting into the wound. Additionally,initiating the reduced pressure treatment at the earliest stage possibleis also advantageous to healing of the wound.

Additionally, embodiments disclosed or incorporated by reference herein,such as those disclosed in U.S. patent application Ser. No. 13/092,042,Great Britain Patent Application Nos. 1015656.0, 1006986.2, 1006983.9,1006985.4, 1006988.8, and 1008347.5 comprise improved wound dressingcomponents. All embodiments, components, features, and other details ofsuch disclosures are hereby incorporated by reference herein as if madepart of this disclosure, and can be used in place of or in combinationwith any of the components, features, and other details of theembodiments disclosed herein. For example, in some embodiments, thewound dressing can be configured to act as a buffer to help preventcompression or shear forces exerted on the wound dressing, for exampledue to patient movement, from harming a healing wound. Embodiments ofthe wound dressing may act as a waste canister to collect and storewound exudate removed from a wound site, and also relate to themanagement of solid build-up in a wound dressing covering a wound sitewhilst TNP therapy is applied. Further, embodiments disclosed hereinrelate to a method and suction port for applying negative pressure to awound dressing and a method of manufacturing a suction port and wounddressing.

Moreover, some embodiments disclosed herein are directed to systems thatinclude negative pressure therapy apparatuses and dressings, and methodsand algorithms for operating such negative pressure therapy apparatusesfor use with negative pressure therapy dressings. In some embodiments, anegative pressure therapy apparatus comprises a pump assembly configuredto, inter alia, provide negative pressure to a wound. Some embodimentsof pump assemblies disclosed herein comprise novel and inventive controllogic configured to control the operation of the pump assembly. Forexample, some embodiments comprise novel and inventive control logicconfigured to control the operation of a pump assembly in response tomonitoring and detecting various operating conditions, such as presenceand/or severity of a leak or leaks in the system, rate of flow of fluid(e.g., air, liquid and/or solid exudate, etc.) aspirated from a wound,and the like. In some embodiments, the control logic can be configuredto detect a leak or leaks in a system (e.g., leak or leaks in thedressing that is in fluid communication with the pump, leak or leaks inthe seal created by the dressing over the wound, etc.) as well as tocontrol the operation of the pump assembly when such leak or leaks aredetected. In some embodiments, the pump assembly can be configured todistinguish between at least a normal or low leak (e.g., a leak that hasa relatively low flow rate), a high leak (e.g., a leak that has arelatively high flow rate), and a very high leak (e.g., a leak that hasa relatively very high flow rate). Some embodiments can further beconfigured to also distinguish between the aforementioned leaks and anextremely high leak.

In some embodiments, the pump assembly can comprise a source of negativepressure, such as a miniature, disposable pump, powered by a powersource, such as a battery source. The pump assembly can be configured toprovide therapy for a predetermined period of time, such asapproximately 1 day, 2-10 days, etc. In some embodiments, the pumpassembly can be required to provide uninterrupted therapy for suchperiod of time. In some embodiments, the pump assembly can be configuredto deactivate itself a predetermined period of time (e.g., 7 days) afteran initial activation. The algorithms or logic disclosed herein can helpthe pump assembly operate more efficiently and conserve power, forexample but without limitation, battery power.

In some embodiments, the pump assembly can be configured to monitor theduty cycle of the source of negative pressure (e.g., a pump). As is usedherein, “duty cycle” reflects the amount of time the source of negativepressure is active or running over a period of time. In other words, theduty cycle reflects time that the source of negative pressure is in anactive state as a fraction of total time under consideration. This canbe represented mathematically as:

DC=t/T,   (1)

where DC is the duty cycle, t is the duration that the source ofnegative pressure is active, and T is the total time underconsideration. Duty cycle can be measured as an absolute value (e.g., Xseconds), a proportion (e.g., 1/X), a percentage (e.g., X %), etc. Forexample, if over a period of 1 minute the source of negative pressurehas been on (or operating) for 6 seconds and off (or not operating) for54 seconds, the duty cycle can be represented as 6 seconds, 1/10, 10%,etc.

In some embodiments, the pump assembly can include a controllerconfigured to monitor the duty cycle of the source of negative pressure.Duty cycle measurements can reflect a level of activity of the source ofnegative pressure. For example, duty cycle can indicate that the sourceof negative pressure is operating normally, working hard, workingextremely hard, etc. Moreover, duty cycle measurements, such as periodicduty cycle measurements, can reflect various operating conditions, suchas presence and/or severity of leaks in the system, rate of flow offluid (e.g., air, liquid and/or solid exudate, etc.) aspirated from awound, and the like. Based on the duty cycle measurements, such as bycomparing the measured duty cycle with a set of thresholds (e.g.,determined in calibration), the controller can execute and/or beprogrammed to execute algorithms or logic that control the operation ofthe system in accordance with various system requirements. For example,duty cycle measurements can indicate presence of a high leak in thesystem, and the controller can be programmed to indicate this conditionto a user (e.g., patient, caregiver, physician, etc.) and/or temporarilysuspend or pause operation of the source of negative pressure in orderto conserve power.

In some embodiments, the system can be configured to monitor the rate offlow by any other suitable means. The pump assembly can be configured touse flow meters (e.g., mechanical, pressure-based, optical, mass,thermal mass, electromagnetic, sonic, ultrasonic, laser Doppler, etc.),anemometers, pressure transducers or sensors, electromagnetic sensors(e.g., sensors configured to measure pump speed, such as Hall sensors),electromagnetic measurements (e.g., measuring the current and/or powerdraw of the pump, measuring current and/or power drain of the powersource, measuring the remaining capacity of the power source, etc.) orany combination thereof. Based on the monitored rate of flow, such as bycomparing the rate of flow with a set of thresholds (e.g., determined incalibration), the controller can execute and/or be programmed to executealgorithms or logic that control the operation of the system inaccordance with various system requirements. For example, the controllercan be configured to obtain periodic measurements from a pressure sensoror obtain periodic feedback from a pump motor. The pressure sensor canmeasure pressure under the dressing. The controller can determine therate of flow, for example, by determining a pressure gradient, rate ofchange of pressure, and/or pressure decay rate. For instance, a positivepressure gradient (e.g., one that is increasing) can reflect anincreasing rate of flow as (e.g., a leak) in relation to a threshold,and the controller can be programmed to indicate this condition to theuser.

In some embodiments, the system can be provided for treatment of awound. The dressing can create a substantially sealed or closed spacearound the wound (e.g., under the dressing), and the pump assembly canhave a sensor which can periodically or continuously measure or monitora level of pressure in this space. The pump assembly or a controllerthereof can be configured to control the level of pressure in the space(e.g., under the dressing) between a first negative pressure set pointlimit and at least a second negative pressure set point limit. In someembodiments, the first set point limit can be approximately −70 mmHg, orfrom approximately −60 mmHg or less to approximately −80 mmHg or more.In some embodiments, the second set point limit can be approximately −90mmHg, or from approximately −80 mmHg or less to approximately −100 mmHgor more.

In some embodiments, the system can be configured to include “retry”functionality and/or logic. The pump assembly can be configured tomonitor a level of negative pressure under the dressing (which cancorrespond to the level of negative pressure in the wound cavity),compare the monitored level to a desired negative pressure level (e.g.,first set point, second set point, etc.), and suspend or pause therapyif the desired negative pressure level is not reached during a certaintime interval. Following the suspension or pause of therapy, the pumpassembly can be configured to restart therapy (e.g., restart the sourceof negative pressure) and attempt to again generate the desired negativepressure level under the dressing. Retry functionality can, forinstance, conserve battery power and allow transient and/ornon-transient leaks to become resolved without user intervention orallow the user to fix the leak (e.g., straighten the dressing, fix theseal, check the connection or connections, etc.). In some embodiments, acontroller can execute and/or be programmed to execute retryfunctionality and/or logic.

In some embodiments, the system can be configured to provide“play/pause” functionality and/or logic via a switch, button, etc.located on the exterior of the pump assembly's housing or any othersuitable place where it can be accessed by the user. Play/pausefunctionality can allow the user to suspend and/or restart therapy(e.g., pause and/or restart the pump). The pump assembly can beconfigured to automatically restart therapy following a certainpredetermined or variable pause interval. The pump assembly can beconfigured to automatically restart therapy upon expiration of suchinterval and/or indicate to the user expiration of such interval.

In some embodiments, the system can be configured to provide indication,alarms, etc. to the user reflecting operating conditions. The system caninclude visual, audible, tactile, and other types of indicators and/oralarms configured to signal to the user various operating conditions.Such conditions include system on/off, standby, pause, normal operation,dressing problem, leak, error, and the like. The indicators and/oralarms can include speakers, displays, light sources, etc., and/orcombinations thereof. For example, indication can be provided byactivating or deactivating the source of negative pressure, reducingnegative pressure level generated by the source of negative, loweringthe amount of power used by the source of negative pressure, etc. or anycombination thereof.

FIG. 1 illustrates an embodiment of a reduced pressure wound treatmentapparatus 100 comprising a wound dressing 102 in combination with a pumpassembly 104. In any of the apparatus embodiments disclosed herein, asin the embodiment illustrated in FIG. 1, the pump assembly can be acanisterless pump assembly (meaning that the pump assembly does not havean exudate or liquid collection canister). However, any of the pumpembodiments disclosed herein can be configured to include or support acanister. Additionally, in any of the apparatus embodiments disclosedherein, any of the pump assembly embodiments can be mounted to orsupported by the dressing, or adjacent to the dressing. The dressing 102may be placed over a wound (not illustrated) as described in greaterdetail in U.S. patent application Ser. No. 13/092,042, which disclosureis hereby incorporated by reference and made part of this disclosure,and a conduit 106 may then be connected to the dressing 102. Dressing102 or any other dressing disclosed herein can have any of thematerials, sizes, components, or other details of any of the dressingembodiments disclosed in U.S. patent application Ser. No. 13/092,042,and such embodiments and illustrations thereof are hereby incorporatedby reference in their entireties as if made part of this disclosure. Theconduit 106 or any other conduit disclosed herein can be formed frompolyurethane, PVC, nylon, polyethylene, silicone, or any other suitablematerial.

Some embodiments of the dressing 102 can have a port 108 configured toreceive an end of the conduit 106 (e.g., the first end 106 a of theconduit 106), though such port 108 is not required. In some embodiments,the conduit can otherwise pass through and/or under the dressing 108 tosupply a source of reduced pressure to a space between the dressing 102and the wound so as to maintain a desired level of reduced pressure insuch space. Some embodiments of the apparatus 100 con be configured suchthat the first end 106 a of the conduit 106 is preattached to the port108. The conduit 106 can be any suitable article configured to provideat least a substantially sealed fluid flow pathway between the pumpassembly 104 and the dressing 102, so as to supply the reduced pressureprovided by the pump assembly 104 to the dressing 102.

The dressing 102 can be provided as a single article with all wounddressing elements (including the port 108) pre-attached and integratedinto a single unit. The wound dressing 102 may then be connected, viathe conduit 106, to a source of negative pressure such as the pumpassembly 104. In some embodiments, though not required, the pumpassembly 104 can be miniaturized and portable, although largerconventional pumps such as the EZ CARE™ pump can also be used with thedressing 102.

It will be understood that embodiments of the present invention aregenerally applicable to use in topical negative pressure (“TNP”) therapysystems. Briefly, negative pressure wound therapy assists in the closureand healing of many forms of “hard to heal” wounds by reducing tissueoedema, encouraging blood flow and granular tissue formation, and/orremoving excess exudate and can reduce bacterial load (and thusinfection risk). In addition, the therapy allows for less disturbance ofa wound leading to more rapid healing. TNP therapy systems can alsoassist in the healing of surgically closed wounds by removing fluid andby helping to stabilize the tissue in the apposed position of closure. Afurther beneficial use of TNP therapy can be found in grafts and flapswhere removal of excess fluid is important and close proximity of thegraft to tissue is required in order to ensure tissue viability.

The wound dressing 102 can be located over a wound site to be treated.The dressing 102 can form a substantially sealed cavity or enclosureover the wound site. It will be appreciated that throughout thisspecification reference is made to a wound. In this sense it is to beunderstood that the term wound is to be broadly construed andencompasses open and closed wounds in which skin is torn, cut orpunctured or where trauma causes a contusion, or any other surficial orother conditions or imperfections on the skin of a patient or otherwisethat benefit from reduced pressure treatment. A wound is thus broadlydefined as any damaged region of tissue where fluid may or may not beproduced. Examples of such wounds include, but are not limited to, acutewounds, chronic wounds, surgical incisions and other incisions, subacuteand dehisced wounds, traumatic wounds, flaps and skin grafts,lacerations, abrasions, contusions, burns, diabetic ulcers, pressureulcers, stoma, surgical wounds, trauma and venous ulcers or the like. Insome embodiments, the components of the TNP system described herein canbe particularly suited for incisional wounds that exude a small amountof wound exudate.

Some embodiments of the apparatus are designed to operate without theuse of an exudate canister. The dressing 102 can be configured to have afilm having a high water vapour permeability to enable the evaporationof surplus fluid, and can have a superabsorbing material containedtherein to safely absorb wound exudate. Some embodiments of theapparatus are designed for single-use therapy and can be disposed of inan environmentally friendly manner after an approximately maximum usageof from seven to eleven days. The pump can be programmed toautomatically terminate therapy after a desired number of days, e.g.,after seven days, further operation of the pump will not be possible.Some embodiments are designed for longer or repeated usage, and can beconfigured to support an exudate canister.

The apparatus 100 can be manufactured in a wide variety of differentmodels or versions, wherein the size of the dressing 100 can be variedto accommodate a wide range of wound sizes. For example, apparatuses 100can be made having the following sizes of dressings 102 and wound pads(i.e., absorbent elements, not illustrated in FIG. 1).

Approximate Dressing Size Approximate Wound Pad Size 10 cm × 30 cm (4 in× 11.75 in)  5 cm × 20 cm (2 in × 8 in) 15 cm × 15 cm (6 in × 6 in) 10cm × 10 cm (4 in × 4 in) 15 cm × 20 cm (6 in × 8 in) 10 cm × 15 cm (4 in× 6 in) 10 cm × 20 cm (4 in × 8 in)  5 cm × 10 cm (2 in × 4 in) 20 cm ×20 cm (8 in × 8 in) 15 cm × 15 cm (6 in × 6 in)

Some embodiments of the overlay or dressing can be substantiallyimpervious to air flow and the flow of bacteria or other contaminantsthrough the overlay layer, while being pervious to vapor transmission.

In some embodiments, it may be preferable for the wound site to befilled partially or completely with a wound packing material. This woundpacking material is optional, but may be desirable in certain wounds,for example deeper wounds. The wound packing material can be used inaddition to the wound dressing 102. The wound packing material generallycan comprise a porous and conformable material, for example foam(including reticulated foams), and gauze. Preferably, the wound packingmaterial is sized or shaped to fit within the wound site so as to fillany empty spaces. The wound dressing 102 can then be placed over thewound site and wound packing material overlying the wound site. When awound packing material is used, once the wound dressing 102 is sealedover the wound site, TNP is transmitted from a pump through the wounddressing 102, through the wound packing material, and to the wound site.This negative pressure draws wound exudate and other fluids orsecretions away from the wound site.

In some embodiments, the tubing 106 can have a connector 112 positionedat a second end 106 b of the tubing 106. The connector 112 can beconfigured to couple with a short length of conduit 114 projecting fromthe pump assembly 104, with a mating connector 114 a in communicationwith the short length of conduit 114, with a connector supported by thepump housing (as described in greater detail below), or otherwise. Thelength of the tubing 114 in some embodiments can be approximately 14 mm(0.55 in), or from approximately 0.5 in to approximately 5 inches. Theshort length of conduit or tubing 114 can decrease the discomfort to apatient while laying or otherwise resting on the pump and connector 112.Configuring the pump assembly 104 and tubing 106 so that the tubing 106can be quickly and easily removed from the pump assembly 104 canfacilitate or improve the process of dressing or pump changes, ifnecessary. Any of the pump embodiments disclosed herein can beconfigured to have any of the connection configurations disclosed hereinbetween the tubing and the pump.

In some embodiments, as in the illustrated embodiment, the pump assembly104 can be of a sufficiently small and portable size to be supported ona user's body or in a user's clothing. For example, the pump assembly104 can be sized to be attached using adhesive medical tape or otherwiseto a person's skin in a comfortable location, adjacent to or on thedressing 102 or otherwise. Further, the pump assembly 104 can be sizedto fit within a person's pants or shirt pocket, or can be tethered to aperson's body using a lanyard, pouch, or other suitable device orarticle.

In some embodiments, the pump assembly 104 can be powered by one or morebatteries (for example, two batteries) and can weigh approximately 84grams, or less than 90 grams, including the weight of the batteries. Insome embodiments, the pump assembly 104 can have any desired number ofbatteries and can weigh from approximately 80 grams to approximately 90grams, or from approximately 75 grams to approximately 100 grams, orbetween any values within the foregoing ranges. For example, the weightand/or size of the pump assembly 104 could be reduced by reducing thebattery size and/or weight (to, for example, AAA sized batteries, orsmaller) or the pump size and/or weight.

Further, some embodiments of the pump assembly 104 can be sized to havea total volume defined by an outside surface of the pump ofapproximately 92.5 cubic centimeters (approximately 5.6 cubic inches),or 92.5 cubic centimeters (5.6 cubic inches) or less, or between 75cubic centimeters or less and 115 cubic centimeters or more, or between85 cubic centimeters and 100 cubic centimeters. Additionally, the pumpassembly 104 can be further miniaturized using techniques known to oneof ordinary skill in the art to sizes in the range of approximately 40cubic centimeters, or 40 cubic centimeters or less, or between 30 cubiccentimeters or less and 60 cubic centimeters or more. Some embodimentsof the pump assembly 104 can be sized to have a total volume of between2 cubic inches or less and 6.5 cubic inches or more, or fromapproximately 4 cubic inches to approximately 6 cubic inches, or betweenany values within the foregoing ranges.

The pump assembly 104 can have an overall outside size that isapproximately 7.2 cm×approximately 6.4 cm×approximately 2.1 cm (or 7.2cm×6.4 cm×2.1 cm), or a maximum of approximately 8.5 cm×approximately8.5 cm×approximately 3 cm. Additionally, the pump assembly 104 can havean overall outside size that is approximately 5.5 cm×approximately 4.8cm×approximately 1.5 cm (or 5.5 cm×4.8 cm×1.5 cm). As mentioned, thesize and weight of the pump assembly 104 can be optimized, as it is inthe embodiments disclosed herein, to make it more comfortable to wear orcarry by the user, thereby affording increased mobility.

The negative pressure range for some embodiments of the presentdisclosure can be approximately −80 mmHg, or between about −20 mmHg and−200 mmHg. Note that these pressures are relative to normal ambientatmospheric pressure thus, −200 mmHg would be about 560 mmHg inpractical terms. In some embodiments, the pressure range can be betweenabout −40 mmHg and −150 mmHg. Alternatively a pressure range of up to−75 mmHg, up to −80 mmHg or over −80 mmHg can be used. Also in otherembodiments a pressure range of below −75 mmHg can be used.Alternatively a pressure range of over approximately −100 mmHg, or even150 mmHg, can be supplied by the apparatus 100. Other details regardingthe operation of the pump assembly 104 are set forth in U.S. patentapplication Ser. No. 13/092,042, and such embodiments, configurations,details, and illustrations thereof are hereby incorporated by referencein their entireties as if made part of this disclosure.

FIGS. 2A-2F are various views of the embodiment of the pump assembly 104illustrated in FIG. 1. FIG. 3A illustrates an embodiment of a wounddressing kit 100 comprising a dressing 102 (which can be any of thedressing embodiments disclosed or incorporated by reference herein), apump assembly 104, a conduit 140, one or more batteries 142 (two beingshown), and one or more sealing strips 148 supported in a firstpackaging element 150. FIG. 3B is a bottom isometric view of theembodiment of the wound dressing kit 100 of FIG. 3A. FIG. 3C is anexploded view of the embodiment of the wound dressing kit 100 of FIG.3A.

With reference to FIGS. 2A-3C, the pump assembly 104 can have a housing120 comprising a first housing member 120 a and a second housing member120 b, a control button 122 (which can also be a switch or other similarcomponent), a battery cover 124, a connector 128, and one or morelights, which can be LED lights. In some embodiments, the pump assembly104 can have more than one button 122, and can have three or more lights132. The lights 132 can be configured to alert a user to a variety ofoperating and/or failure conditions of the pump assembly 104, includingalerting the user to normal or proper operating conditions, pumpfailure, power supplied to the pump or power failure, the condition orvoltage level of the batteries, detection of a leak within the dressingor flow pathway, suction blockage, or any other similar or suitableconditions or combinations thereof.

The housing 120 can be configured such that a sterilization gas, such asethylene dioxide, can penetrate into the housing such that the internalcomponents of the pump assembly 104 are exposed to the sterilization gasduring normal sterilization processes. Typically, the pump will beexposed to the sterilization gas in a chamber that has beensubstantially evacuated of air or any other gas, so that thesterilization gas is drawn into the pump housing 120 and into the otherspaces and chambers within the pump assembly 104. For example, someembodiments of the pump housing 120 can have an unsealed gap surroundingthe connector 128 through which the sterilization gas can pass. Also, insome embodiments, the first housing member 120 a can be joined to thesecond housing member 120 b without the use of a seal therebetween.

For the sterilization process, in some embodiments, the components to besterilized can be subjected to the following steps, inter alia, in anyorder. The components can be placed in a chamber or container that isevacuated to approximately 70 mBarA (or between 67 mBar A and 80 mBarA)for between approximately 15 minutes and 1 hour and 15 minutes. Thecomponents can also be subjected to inert dilution, steam pressure orconditioning, or nitrogen cycles, which can be followed by furtherevacuation cycles. Ethylene oxide or any other suitable sterilizationgas can be introduced into the chamber or container at a pressure setpoint of approximately 482 mBarA (or from approximately 467 mBarA toapproximately 500 mBarA). The components can be exposed to thesterilization gas at a temperature of approximately 46 degrees Celsius(or from approximately 42 degrees Celsius to 49 degrees Celsius), or upto 60 degrees Celsius. The components can be exposed to thesterilization gas for approximately 10 minutes (short cycle) orapproximately 1 hour (long cycle), or from approximately 9 minutes toapproximately 11 minutes (short cycle), or from approximately 59 minutesto approximately 1 hour (long cycle), or longer. The components orchamber can be flushed with nitrogen and/or air and/or degassedthereafter.

The pump assembly 104 can be powered by one or more batteries 142. Thebatteries 142 can be lithium chloride or any other suitable batteriesthat are suitable for exposure to ethylene dioxide and/or othersterilization gases. The batteries 142 can be supported outside of thepump housing 120 so as to minimize or eliminate the chance of anelectrical spark which could cause an explosion in the presence of thesterilization gas or an explosive gas during the sterilization processwhen supported in the packaging element or elements. Additionally, wherethere are a plurality of batteries 142, the batteries can be spacedapart or otherwise separated in the packaging to prevent any power lossor sparking of the batteries during the sterilization process orotherwise before usage.

With reference to FIG. 3A, the batteries 142 and the sealing strip orstrips 148 can be positioned beneath the dressing 102 so that thedressing 102 must be removed from the first packaging element 150 beforethe batteries 142 are removed, thereby suggesting an order by which thecomponents of dressing kit 100 are removed from the packaging 150 and/orapplied to the patient or assembled to the other components comprisingthe apparatus 100.

In some embodiments, the conduit 140 can be positioned within thepackaging 150 so that both ends of the conduit 140 are free or otherwisedisconnected from the other components of the apparatus 100 to improvethe exposure of the internal surfaces of the conduit 140 to and/or toensure complete exposure of the tubing to the sterilization gas. Theends of the conduit 140 can be supported within recesses formed in thefirst packaging element 150.

The first packaging element 150 can have one or more recesses configuredto receive and support the components of the apparatus 100, including arecess 190 for receiving the pump assembly 104, a recess 192 forreceiving the dressing 102, a recess 194 for receiving the one or moresealing strips 148 and/or the conduit 140, a recess 196 for receivingthe conduit 114 and/or connector 114 a, if present, and spaced apartrecesses 200 a and 200 b for the batteries 142. Spacing apart thebatteries can reduce or eliminate the risk of explosion duringsterilization procedures due to the potentially flammable nature ofethylene oxide.

In some embodiments, the first packaging element 150 can be made from amaterial or combination of materials that is sufficiently rigid and/orrobust to hold the batteries, pump and/or other components in placeduring processing or transportation of the dressing kit. For example,some embodiments of the first packaging element 150 can be configured toprovide a compression or interference fit for the components, such asthe batteries, the pump, or other components, sufficient to withstandaccelerations of between approximately 15 G and approximately 25 G, orbetween 1 G and 40 G, or between 1 G and 20 G, or between 25 G and 40 G.Some embodiments of the first packaging element 150 can be configured totightly hold the pump, batteries, tubing (with tubing pinches orrecesses) and other components sufficient to prevent movement ordislodgement of components which could lead to short circuit ormelting/abrasion of the packaging, resulting in damage to the packagingor bacterial ingress while not impeding the ability of the user toremove such components from the packaging when needed.

Additionally, as illustrated, the first packaging element 150 can havegrooves or recesses 193 sized and configured to facilitate the surgeon'sor user's access and removal of the various components of the apparatus100, both with and without a gloved hand. Further, bosses or projections195 can be formed in the first packaging element 150 to provideadditional support and protection to the packaging and kit components.The first packaging element 150 can be made from any suitable materialthat can be sterilized, including a recyclable virgin PETG Blue tinted0.80 Eastman 6763 medical grade provided by Nelipak Custom ThermoformedProducts. The packaging element 150 can be extruded and thermoformedfrom EASTAR™ Chemical Product EASTAR copolyester resin. For example, theraw material, which can be an extruded sheet or film, can bethermoformed using a vacuum and press over a dye tool under elevatedtemperatures. Other suitable materials for the first packaging element150 include polycarbonate, PVC, or any other suitable resin or plasticmaterial. In some embodiments, the first packaging element can be madefrom a material (including a plate, sheet, film, or otherwise) having athickness of 0.8 mm (or approximately 0.8), or a thickness of 0.8 mm orless, or 1.0 mm or less, or between approximately 0.7 mm and 1.2 mm.

A gas permeable cover 151 (also referred to herein as a second packagingelement) can be sealingly positioned over the first packaging element150 to provide a bacteria and contaminant barrier to the contents of thedressing kit 100. For example, a sheet-like layer or film of TYVEK™,paper, or any other suitable material can be sealed to a rim portion 153of the first packaging element 150. The cover 151 can be made from anysuitable material, including TYVEK, which is permeable to thesterilization gas but provides a barrier to bacteria and othercontamination. The cover 151 can be opaque, clear, or translucent.

The cover 151 can be sealingly coupled with the first packaging element150 after all of the dressing kit components assembled therein.Thereafter, the first packaging element 150, cover 151, and the dressingkit components can be positioned within a sealed, impermeable bag havinga TYVEK or other sterilization gas permeable patch of material over anopening formed in the bag to permit the sterilization gas to enter thebag and sterilize the components of the dressing kit.

FIGS. 4A and 4B are first and second exploded views of the embodiment ofthe pump assembly 104 of FIG. 1, showing the first housing member 120 aseparated from the second housing member 120 b. FIGS. 5A and 5B arefirst and second views of the first housing member 120 a. FIGS. 6A and6B are first and second views of the second housing member 120 b. Withreference to FIGS. 4A-6B, some embodiments of the pump assembly 104 canhave a battery compartment 220 supported or formed within the housing120. One or more battery contacts 222 can be supported within thebattery compartment 220. One or more electrical wires 224 can connectthe battery contacts 222 to a pump 232 and/or a control board 230. Thepump assembly 104 can be assembled in a clean room to reduce the risk ofcontamination or bioburden that the pump is exposed to or can collectduring assembly.

In some embodiments, the pump 232 can comprise a motor, an inlet port orconnector 250, and an outlet port 252. The pump 232 can have one or morevalves therein. For example, a first valve can be positioned within thepump 232 adjacent the inlet port 250. Additionally, a second valve canbe positioned within the pump 232 adjacent the outlet port 252. The pump232 can define a flow pathway through the inlet port 250, through thefirst and second valves, and out the outlet port 252.

In some embodiments, the battery contacts 222 can also be configured tohave polarity protection. For example, similar to the one or moreprotrusions 124 d adjacent to the battery contact 125, the one or moreof the battery contacts 222 can have plastic or other protrusions (notillustrated) adjacent to the contacts to inhibit the contact between thebattery contact 222 and the incorrect side of a battery that is insertedinto the battery compartment in the incorrect orientation. For example,the one or more protrusions can be sized and configured to prevent thenegative side of a standard cylindrical battery from contacting thebattery contact 222 adjacent to the one or more protrusions, whilepermitting a positive side of such battery to contact the batterycontact 222. Generally, with this configuration, the battery cangenerally only make contact with the contact 222 if the battery isinserted in the battery compartment 220 in the correct orientation,thereby providing polarity protection to the pump assembly 104. Theprotrusions will preferably be made from a non-conductive material.Alternatively or additionally, the control board 230 can be configuredto have polarity protective features or components. Additionally, thecontrol board 230 can have one or more fuses to protect againstoverpower conditions or surge power conditions.

The pump assembly 104 can have a flow manifold 240 and a one-way flowvalve 246 in communication with a fluid flow pathway within the pumpassembly 104. The one-way flow valve 246 (also referred to as a checkvalve) can be a diaphragm valve made from silicone or any other suitableelastomeric or soft material, including without limitation,polyurethane, viton, nitrile rubber, neoprene, Teflon, and othersuitable materials. Other suitable valves for the one-way flow valveare, for example and without limitation, umbrella valves, ball valves,reed valves, duckbill valves. In some embodiments, the leakage rate ofthe one-way flow valve 246 can be approximately 0.05 mL/minute. In someembodiments, the one-way flow valve 246 can be positioned within thepump 232 or in place of one of the valves positioned within the pump232.

The manifold 240 and/or the one-way flow valve 246 can be incommunication with the connector 128. In some embodiments, the one-wayflow valve 246 can be supported within the manifold 240, and themanifold 240 can be substantially sealingly coupled with the inlet portor connector 250 on the pump 232 or otherwise supported within thehousing 120 so as to be in fluid communication with the inlet port orconnector 250. For example, with reference to FIGS. 4A and 4B, themanifold 240 can be assembled with the pump 232 such that the inletconnector 250 is received within the opening 261 formed in the manifold240. Air and or other gas can exit the pump 232 through outlet port orconnector 252. During sterilization, the pump 232 can be configured suchthat the sterilization gas can penetrate into the internal spaces orchambers of the pump 232, to ensure that the entire pump 232 (bothinternally and externally) have been sterilized. One or more valves(which can be umbrella valves or any other suitable valve) can bepositioned in the pump 232. For example, without limitation, one or morevalves can be supported in the pump 232, one being positioned adjacentto each of the inlet port 250 and the outlet port 252.

For optimal sterilization, in some embodiments, the sterilization gascan be introduced slowly to optimize the flow of the sterilization gasthrough the valves and to prevent the pressure from the sterilizationgas from completely closing the valves. As mentioned, the valves (suchas the first and second valves) can be configured to be somewhat leaky,thereby permitting the flow of sterilization gas to advance past thevalves to sterilize the internal components of the pump 232. Forexample, the valves can permit a leakage flow rate of fluid therethrough(i.e., flow rate through the valve when the valve is in a closedposition) at a rate of between 0.1 mL/min and 10 mL/min or more atnominal or typical working pressures (i.e., at nominal working pressuresof the fluid in the conduit) or at nominal or typical sterilizationpressures. In some configurations, the portion of the flow pathwaybetween the two valves, or between the valves and the one-way valve, canbe the most challenging portion of the flow path or pump assembly 104 tosterilize.

Some embodiments of the pump assembly can have a piezoelectric pump.Some piezoelectric pumps or other pumps disclosed herein can have or canbe configured to have orifices to perform the valve functions such that,when the pump is at rest, the flow rate through the pump can be as highas 200 mL/min. Therefore, in some embodiments, where the pump rate canbe as high as approximately 300 mL/min or 320 mL/min or otherwise, thefirst and second valves (which can be orifices) can each have a leakagerate of up to approximately 200 mL/min.

The pump 232 can be of any suitable type such as, without limitation, arotary diaphragm pump or other diaphragm pump, a piezoelectric pump, aperistaltic pump, a piston pump, a rotary vane pump, a liquid ring pump,a scroll pump, a diaphragm pump operated by a piezoelectric transducer,or any other suitable pump or micropump or any combinations of theforegoing. The pump 232 can be, for example, a standard off-the-shelfvacuum pump such as the Koge Electronics KPV8A-3A pump. The pump 232 canalso be a KNF diaphragm pump or any suitable KNF pump.

Some embodiments of the pump can be as light as approximately 10 grams,or between approximately 6 grams and 15 grams, or between any valueswithin the foregoing range. The pump 232 can have a pump capacity ofapproximately 500 mL per minute, or between approximately 300 mL perminute or less and approximately 600 mL per minute or more, or betweenapproximately 400 mL per minute and approximately 500 mL per minute, orbetween any values within the foregoing ranges. In some embodiments, thepump assembly 104 could comprise two or more pumps 232. For example, thepump assembly 104 could have a first pump having a high flow rate,configured to provide a rapid drawdown of the space between the woundoverlay and the wound, and a second, smaller capacity pump configured tomaintain the level of reduced pressure of the space between the woundoverlay and the wound after the initial draw down. In some embodiments,the pump flow rate can be approximately 20 times the leak alarm flowrate, which can be set at approximately 15 milliliters per minute.

As mentioned, the connector 128 can be a threaded connector (asillustrated) that can threadingly receive a mating threaded connectorcoupled with the end of the tubing 106. The threaded connector 128 canbe of a non-standard size as compared to other medical connectors, toprevent a medical practitioner from inadvertently attaching a standardluer connector (such as a connector from an intravenous line) thereto.

Alternatively, not illustrated, the connector 128 can be a standardtubing connector (such as a nipple connector) configured to sealinglyreceive the tubing thereover such that a separate mating connector onthe end of the tubing 106 can be omitted.

The manifold 240 can have a separate port 260 which can be configured toreceive a conduit or connector 262 of a pressure monitor. The pressuremonitor can be supported by the control board 230 and can be configuredto monitor a level of pressure in the fluid flow passageway. Thepressure monitor can be configured to protect the motor 232 fromexceeding a predefined threshold pressure. In some embodiments, thepressure monitor can be calibrated to not exceed 175+/−50 mmHg. In someembodiments, the pressure monitor can be calibrated to not exceed 235mmHg. The pressure monitor can be configured to cut power to the motorif the pressure reading reaches a predetermined value, and be configuredto resume when the pressure level drops below the predetermined value ora second predetermined value that can be higher or lower than the firstpredetermined value. Additionally, the pump assembly 104 can beprogrammed to prevent such over-pressurization. The pump assembly 104can be configured such that the software provides the primary mechanismfor preventing over-pressurization, and the pressure monitor can providebackup over-pressurization protection.

The pump 232 can have a layer of open foam or other material wrapped atleast partially around an outside surface of the pump 232 to reduce thenoise and vibration produced by the pump 232. All of these componentscan be supported within the first and second pump housing members 120 a,120 b, which can be secured together with any suitable fasteners 270(for example, a pair of screws). One or more labels 270 can be affixedto an outside surface of the housing 120. Additionally, in someembodiments, the pump 232 can have one or more weights, cushions, foam(such as a viscoelastic foam), plastic (such as ABS, polyurethane,urethane, or otherwise), or other pads, panels, sheets, or segmentssupported by the pump 232 or positioned adjacent to one or more outsidesurfaces of the pump. Some embodiments can have mass based or compliantdamping materials. Such components or materials (not illustrated) candamp vibration and/or attenuate noise produced by the pump.

For example, one or more weights (made from steel, metal, or any othersuitable material) can be supported or attached to an outside surface ofthe pump 232 or any other pump embodiment disclosed herein. The steelweights can weigh approximately 1.8 grams, 3.8 grams, or 5.8 grams, orbetween 1 gram and 10 grams or more, or between 1.5 grams and 6 grams.Two or more weights can be supported or attached to an outside surfaceof the pump 232 or any other pump embodiment disclosed herein. Two steelweights each weighing approximately 1.8 grams, 3.8 grams, or 5.8 grams,or between 1 gram and 10 grams or more, or between 1.5 grams and 6grams, can be attached to an outside surface of the pump 232. Each ofthe two plates can be positioned on opposite sides of the motor 232, orotherwise. In some embodiments, four steel weights each weighingapproximately 1.8 grams, 3.8 grams, or 5.8 grams, or between 1 gram and10 grams or more, or between 1.5 grams and 6 grams, can be attached toan outside surface of the pump 232. The plates can be arranged such thattwo plates are positioned on each of two opposite sides of the motor232, or otherwise. In some embodiments, weights can be positionedadjacent to three or more sides of the pump 232 including, for exampleand without limitation, the sides and top surfaces of the pump 232.

With reference to FIG. 4A, the battery cover 124 can have a latch or tabmember 124 a that can be configured to engage with mating feature on thehousing 120 to inhibit the battery cover 124 from becoming inadvertentlyopened when in the closed position. Additionally, guides or protrusions124 b can be formed on the battery cover 124 to facilitate the ease withwhich the battery cover 124 can be opened and closed. The guides 124 bcan engage mating guides or channels 120 c formed in the housing 120.The battery cover 124 can be configured to have a gripping surface, forsingle finger use. For example, without limitation, a plurality ofdepressions 124 c can be formed on a surface of the battery cover 124 toenhance the grip between a user's finger or other object and the battercover 124, to facilitate the opening and closing of the battery cover124.

With reference to FIG. 4B, the battery cover 124 can support one or morebattery contacts or terminals 125 thereon, configured to provide aconnection between the two batteries. The battery cover 124 can furthersupport one or more protrusions 124 d adjacent to the battery contact125. The one or more protrusions 124 d can be sized and configured toprevent the negative side of a standard cylindrical battery fromcontacting the battery contact 125 adjacent to the one or moreprotrusions 124 d, while permitting a positive side of such battery tocontact the battery contact 125. With this configuration, the batterycan generally only make contact with the contact 125 if the battery isinserted in the battery compartment 220 in the correct orientation,thereby providing polarity protection to the pump assembly 104.

With reference to FIGS. 4A and 4B, the housing 120 can have one or moretabs 121 and depressions or channels 123 configured to receive the tabs121 to improve the connection between the two members 120 a, 120 b ofthe housing. The tabs 121 and depressions 123 can hold the edges of thehousing 120 together better to improve the strength of the housing 120and to make the connection tighter between the two members 120 a, 120 bof the housing. The control board 230 can be assembled to the housing 12with similar features.

As described in U.S. patent application Ser. No. 13/092,042, whichdisclosure is hereby incorporated by reference as if fully set forthherein, a lower surface of any of the wound dressing 102 embodimentsdisclosed herein can have an optional wound contact layer. Any of thedressing embodiments disclosed herein can be made without the woundcontact layer. The wound contact layer can be a polyurethane layer orpolyethylene layer or other flexible layer which can be made porous orperforated, for example via a hot pin process, laser ablation process,ultrasound process or in some other way or otherwise made permeable toliquid and gas. The perforations can enable fluid and/or gas to flowthrough the layer. The wound contact layer can help prevent tissueingrowth into the other material of the wound dressing.

The perforations can be sized small enough to meet this requirement butstill allow fluid through. For example, perforations formed as slits orholes having a size ranging from 0.025 mm to 1.2 mm are considered smallenough to help prevent tissue ingrowth into the wound dressing whileallowing wound exudate to flow into the dressing. The wound contactlayer helps hold the whole wound dressing together and helps to createan air tight seal around the absorbent pad in order to maintain negativepressure at the wound. The wound contact layer also acts as a carrierfor an optional lower and upper adhesive layer (not shown). For example,a lower pressure sensitive adhesive can be provided on the undersidesurface 101 of the wound dressing whilst an upper pressure sensitiveadhesive layer can be provided on the upper surface 103 of the woundcontact layer. The pressure sensitive adhesive, which can be a silicone,hot melt, hydrocolloid or acrylic based adhesive or other suchadhesives, can be formed on both sides or optionally on a selected oneor none of the sides of the wound contact layer. When a lower pressuresensitive adhesive layer is utilized this helps adhere the wounddressing to the skin around a wound site.

As mentioned, any dressing embodiments for use in the dressing kitsdisclosed or incorporated by reference herein can have an adhesivecovered bottom (e.g., wound contacting) surface. In some embodiments, asmentioned, the adhesive can be a silicone adhesive including, forexample, polysiloxanes or polyorganosiloxanes or other polymericpressure sensitive silicone adhesives. For example, polydimethylsiloxaneor the like can be used. The adhesive formulation may be a mixture ofalkyl pendant siloxanes, which can be spread and cast as a two part mixwith a catalyst such that a final polymerisation step takes placefollowing casting or spreading. In some embodiments, a dressing layercan have a non-perforated silicone adhesive coating (coat weight 130 gsmnominal) and full spread acrylic adhesive (27 to 37 gsm) coated ontoopposite sides of an extruded EU30 polyurethane clear film (27 to 37gsm). Moisture vapour permeability of some embodiments of such anarrangement can be between approximately 367 gm⁻²/24 hrs toapproximately 405 gm⁻²/24 hrs, or a mean moisture vapour permeability of382 gm⁻²/24 hrs.

Some embodiments or arrangements of a silicone adhesive layer suitablefor dressing embodiments disclosed herein can have a moisture vapourtransmission rate between approximately 350 gm⁻²/24 hrs andapproximately 410 gm⁻²/24 hrs. Aptly, the average moisture vapourpermeability of some embodiments or arrangements of a silicone adhesivelayer suitable for dressing embodiments disclosed herein can beapproximately 380 gm⁻²/24 hrs. Some of the dressing embodimentsdisclosed herein can have a Wacker silres PSA 45 pressure sensitiveadhesive coated thereon.

Additionally, any of the dressing embodiments disclosed herein can havean anti-microbial agent or substance incorporated into the dressing orcoated on one or more surfaces of the dressing. For example, withoutlimitation, a wound contact layer of any dressing embodiments disclosedherein can have nanocrystalline silver agents, silver salts, coppersalts, or gold salts such as, without limitation, those disclosed inU.S. patent application Ser. No. 11/922,894 (titled ANTIMICROBIALBIGUANIDE METAL COMPLEXES), filed May 21, 2008, which application isincorporated by reference herein as if made part of this disclosure,PHMB, chlorohexadine, peroxide, hypochloride, or other bleaches thereinor thereon. Further, an absorbent layer of any dressing embodimentsdisclosed herein can have silver sulphur diazine or any of thepreviously mentioned substances or active agents therein or thereon.These may be used separately or together. These respectively caneliminate micro-organisms in the wound and micro-organisms in theabsorption matrix. As a still further option, other active components,for example, pain suppressants such as ibuprofen or healing agents canbe incorporated into the dressing. Also agents which enhance cellactivity, such as growth factors or that inhibit enzymes, such as matrixmetalloproteinase inhibitors, such as tissue inhibitors ofmetalloproteinase (TIMPS) or zinc chelators, can be incorporated intothe dressing. Odor trapping elements such as activated carbon,cyclodextrine, zeolite or the like can also be included in the absorbentlayer or other portions or components of the dressing, or above thefilter layer.

A layer of porous material can be located above the wound contact layer.This porous layer, or transmission layer, allows transmission of fluidincluding liquid and gas away from a wound site into upper layers of thewound dressing. In particular, the transmission layer can ensure that anopen air channel can be maintained to communicate negative pressure overthe wound area even when the absorbent layer has absorbed substantialamounts of exudates. The layer should remain open under the typicalpressures that will be applied during negative pressure wound therapy asdescribed above, so that the whole wound site sees an equalized negativepressure. The layer can be formed of a material having a threedimensional structure. For example, a knitted or woven spacer fabric(for example Baltex 7970 weft knitted polyester) or a non-woven fabriccan be used. Other materials can be utilized, and examples of suchmaterials are described in U.S. patent application Ser. No. 13/092,042,which are hereby incorporated by reference and made part of thisdisclosure.

In some embodiments, the transmission layer can have a 3D polyesterspacer fabric layer. This layer can have a top layer (that is to say, alayer distal from the wound-bed in use) which is a 84/144 texturedpolyester, and a bottom layer (that is to say, a layer which liesproximate to the wound bed in use) which can be a 100 denier flatpolyester and a third layer formed sandwiched between these two layerswhich is a region defined by a knitted polyester viscose, cellulose orthe like monofilament fiber. Other suitable materials and other linearmass densities of fiber can be used.

This differential between filament counts in the spaced apart layershelps control moisture flow across the transmission layer. Particularly,by having a filament count greater in the top layer, that is to say, thetop layer is made from a yarn having more filaments than the yarn usedin the bottom layer, liquid tends to be wicked along the top layer morethan the bottom layer. In use, this differential tends to draw liquidaway from the wound bed and into a central region of the dressing wherethe absorbent layer helps lock the liquid away or itself wicks theliquid onwards towards the cover layer where it can be transpired.

Preferably, to improve the liquid flow across the transmission layer(that is to say perpendicular to the channel region formed between thetop and bottom spacer layers, the 3D fabric is treated with a drycleaning agent (such as, but not limited to, Perchloro Ethylene) to helpremove any manufacturing products such as mineral oils, fats and/orwaxes used previously which might interfere with the hydrophiliccapabilities of the transmission layer. In some embodiments, anadditional manufacturing step can subsequently be carried in which the3D spacer fabric is washed in a hydrophilic agent (such as, but notlimited to, Feran Ice 30 g/l available from the Rudolph Group). Thisprocess step helps ensure that the surface tension on the materials isso low that liquid such as water can enter the fabric as soon as itcontacts the 3D knit fabric. This also aids in controlling the flow ofthe liquid insult component of any exudates.

Again, as described in greater detail in U.S. patent application Ser.No. 13/092,042, a layer of absorbent material can be provided above thetransmission layer. The absorbent material which can be a foam ornon-woven natural or synthetic material and which can optionally includeor be super-absorbent material forms a reservoir for fluid, particularlyliquid, removed from the wound site and draws those fluids towards acover layer. The material of the absorbent layer can prevent liquidcollected in the wound dressing from flowing in a sloshing manner. Theabsorbent layer can also help distribute fluid throughout the layer viaa wicking action so that fluid is drawn from the wound site and storedthroughout the absorbent layer. This helps prevent agglomeration inareas of the absorbent layer. The capacity of the absorbent materialmust be sufficient to manage the exudates flow rate of a wound whennegative pressure is applied. Since in use the absorbent layerexperiences negative pressures the material of the absorbent layer ischosen to absorb liquid under such circumstances. A number of materialsexist that are able to absorb liquid when under negative pressure, forexample superabsorber material. The absorbent layer can be manufacturedfrom ALLEVYN™ foam, Freudenberg 114-224-4 and/or Chem-Posite™11C-450, orany other suitable material.

In some embodiments, the absorbent layer can be a layer of non-wovencellulose fibers having super-absorbent material in the form of dryparticles dispersed throughout. Use of the cellulose fibers introducesfast wicking elements which help quickly and evenly distribute liquidtaken up by the dressing. The juxtaposition of multiple strand-likefibers leads to strong capillary action in the fibrous pad which helpsdistribute liquid. In this way, the super-absorbent material isefficiently supplied with liquid. Also, all regions of the absorbentlayer are provided with liquid.

The wicking action also assists in bringing liquid into contact with theupper cover layer to aid increase transpiration rates of the dressing.The wicking action also assists in delivering liquid downwards towardsthe wound bed when exudation slows or halts. This delivery process helpsmaintain the transmission layer and lower wound bed region in a moiststate which helps prevent crusting within the dressing (which could leadto blockage) and helps maintain an environment optimized for woundhealing.

In some embodiments, the absorbent layer can be an air-laid material.Heat fusible fibers can optionally be used to assist in holding thestructure of the pad together. It will be appreciated that rather thanusing super-absorbing particles or in addition to such use,super-absorbing fibers can be utilized according to some embodiments ofthe present invention. An example of a suitable material is the ProductChem-Posite™ 11 C available from Emerging Technologies Inc (ETi) in theUSA.

Optionally, the absorbent layer can include synthetic stable fibersand/or bi-component stable fibers and/or natural stable fibers and/orsuper-absorbent fibers. Fibers in the absorbent layer can be securedtogether by latex bonding or thermal bonding or hydrogen bonding or acombination of any bonding technique or other securing mechanism. Insome embodiments, the absorbent layer is formed by fibers which operateto lock super-absorbent particles within the absorbent layer. This helpsensure that super-absorbent particles do not move external to theabsorbent layer and towards an underlying wound bed. This isparticularly helpful because when negative pressure is applied there isa tendency for the absorbent pad to collapse downwards and this actionwould push super-absorbent particle matter into a direction towards thewound bed if they were not locked away by the fibrous structure of theabsorbent layer.

The absorbent layer can comprise a layer of multiple fibers. Preferably,the fibers are strand-like and made from cellulose, polyester, viscoseor the like. Preferably, dry absorbent particles are distributedthroughout the absorbent layer ready for use. In some embodiments, theabsorbent layer comprises a pad of cellulose fibers and a plurality ofsuper absorbent particles. In additional embodiments, the absorbentlayer is a non-woven layer of randomly orientated cellulose fibers.

Super-absorber particles/fibers can be, for example, sodium polyacrylateor carbomethoxycellulose materials or the like or any material capableof absorbing many times its own weight in liquid. In some embodiments,the material can absorb more than five times its own weight of 0.9% W/Wsaline, etc. In some embodiments, the material can absorb more than 15times its own weight of 0.9% W/W saline, etc. In some embodiments, thematerial is capable of absorbing more than 20 times its own weight of0.9% W/W saline, etc. Preferably, the material is capable of absorbingmore than 30 times its own weight of 0.9% W/W saline, etc. The absorbentlayer can have one or more through holes located so as to underlie thesuction port.

The dressing 102 can have a gas impermeable, but moisture vaporpermeable, cover layer extending across the width of the wound dressing.The cover layer, which can for example be a polyurethane film (forexample, Elastollan SP9109) or any other suitable material having apressure sensitive adhesive on one side, is substantially gasimpermeable, thereby creating a substantially sealed enclosure over thewound. In this way an effective chamber is made between the cover layerand a wound site where a negative pressure can be established. The coverlayer can be sealed to the wound contact layer in a border region aroundthe circumference of the dressing, ensuring that no air is drawn inthrough the border area, for example via adhesive or welding techniques.The cover layer can protect the wound from external bacterialcontamination (bacterial barrier) and allows liquid from wound exudatesto be transferred through the layer and evaporated from the film outersurface. The cover layer can have a polyurethane film and an adhesivepattern spread onto the film. The polyurethane film is moisture vaporpermeable and may be manufactured from a material that has an increasedwater transmission rate when wet.

An orifice can be provided in the cover film to allow a negativepressure to be applied to the dressing 102. As mentioned, in someembodiments, a suction port 108 can be sealed to the top of the coverfilm over the orifice, which can communicate negative pressure throughthe orifice. The port may be adhered and sealed to the cover film usingan adhesive such as an acrylic, cyanoacrylate, epoxy, UV curable or hotmelt adhesive. The port 108 can be formed from a soft polymer, forexample a polyethylene, a polyvinyl chloride, a silicone or polyurethanehaving a hardness of 30 to 90 on the Shore A scale.

The dressing 102 can have a filter element that is impermeable toliquids, but permeable to gases. The filter element can act as a liquidbarrier, to substantially prevent or inhibit liquids from escaping fromthe wound dressing, as well as an odor barrier. The filter element mayalso function as a bacterial barrier. In some embodiments, the pore sizeof the filter element can be approximately 0.2 μm. Suitable materialsfor the filter material of the filter element include 0.2 micron Gore™expanded PTFE from the MMT range, PALL Versapore™ 200R, and Donaldson™TX6628. The filter element thus enables gas to be exhausted through theorifice. Liquid, particulates and pathogens however are contained in thedressing. Other details regarding the filter are disclosed in U.S.patent application Ser. No. 13/092,042 and incorporated by referenceherein.

The wound dressing 102 and its methods of manufacture and use asdescribed herein may also incorporate features, configurations andmaterials described in the following patents and patent applications,each of which is incorporated by reference in their entireties herein asif made part of this disclosure: U.S. Pat. Nos. 7,524,315, 7,708,724,and 7,909,805; U.S. Patent Application Publication Nos. 2005/0261642,2007/0167926, 2009/0012483, 2009/0254054, 2010/0160879, 2010/0160880,2010/0174251, 2010/0274207, 2010/0298793, 2011/0009838, 2011/0028918,2011/0054421, and 2011/0054423; as well as U.S. application Ser. No.12/941,390, filed Nov. 8, 2010, Ser. No. 29/389,782, filed Apr. 15,2011, and Ser. No. 29/389,783, filed Apr. 15, 2011. From theseincorporated by reference patents and patent applications, features,configurations, materials and methods of manufacture or use for similarcomponents to those described in the present disclosure may besubstituted, added or implemented into embodiments of the presentapplication.

In operation, the wound dressing 102 is sealed over a wound site forminga wound cavity. The pump assembly 104 provides a source of a negativepressure to the dressing 102. Fluid is drawn towards the orifice throughthe wound dressing from a wound site below the wound contact layer. Thefluid moves towards the orifice through the transmission layer. As thefluid is drawn through the transmission layer, wound exudate is absorbedinto the absorbent layer.

The general shape of the wound dressing can be square, ovular,rectangular, or otherwise. The dressing can have rounded corner regions.It will be appreciated that wound dressings according to otherembodiments of the present invention can be shaped differently such assquare, circular or elliptical dressings, or the like.

The desired size of the wound dressing 102 can be selected based on thesize and type of wound it will be used in. In some embodiments, thewound dressing 102 can measure between 20 and 40 cm on its long axis,and between 10 to 25 cm on its short axis. For example, dressings can beprovided in sizes of approximately 10×20 cm, 10×30 cm, 10×40 cm, 15×20cm, and 15×30 cm, as described above.

In some embodiments, the wound dressing 102 can be a square-shapeddressing with sides measuring between 15 and 25 cm (e.g., 15×15 cm,20×20 cm and 25×25 cm). The absorbent layer can have a smaller area thanthe overall dressing, and in some embodiments may have a length andwidth that are both about 3 to 10 cm shorter, more preferably about 5 cmshorter, than that of the overall dressing 102. In somerectangular-shape embodiments, the absorbent layer may measure betweenapproximately 10 and 35 cm on its long axis, and between 5 and 10 cm onits short axis. For example, absorbent layers can be provided in sizesof 5.6×15 cm or 5×10 cm (for 10×20 cm dressings), 5.6×25 cm or 5×20 cm(for 10×30 cm dressings), 5.6×35 cm or 5×30 cm (for 10×40 cm dressings),10×15 cm (for 15×20 cm dressings), and 10×25 cm (for 15×30 cmdressings). In some square-shape embodiments, the absorbent layer mayhave sides that are between 10 and 20 cm in length (e.g., 10×10 cm for a15×15 cm dressing, 15×15 cm for a 20×20 cm dressing, or 20×20 cm for a25×25 cm dressing). The transmission layer can be of a smaller size thanthe absorbent layer, and in some embodiments can have a length and widththat are both about 0.5 to 2 cm shorter, more preferably about 1 cmshorter, than that of the absorbent layer. In some rectangular-shapeembodiments, the transmission layer may measure between 9 and 34 cm onits long axis and between 3 and 5 cm on its short axis. For example,transmission layers may be provided in sizes of 4.6×14 cm or 4×9 cm (for10×20 cm dressings), 4.6×24 cm or 4×19 cm (for 10×30 cm dressings),4.6×34 cm or 4×29 cm (for 10×40 cm dressings), 9×14 cm (for 15×20 cmdressings), and 9×24 cm (for 15×30 cm dressings). In some square-shapeembodiments, the transmission layer may have sides that are between 9and 19 cm in length (e.g., 9×9 cm for a 15×15 cm dressing, 14×14 cm fora 20×20 cm dressing, or 19×19 cm for a 25×25 cm dressing).

The dressing can contain anti-microbial e.g. nanocrystalline silveragents on the wound contact layer and/or silver sulphur diazine in theabsorbent layer. These may be used separately or together. Theserespectively kill micro-organisms in the wound and micro-organisms inthe absorption matrix. As a still further option other activecomponents, for example, pain suppressants, such as ibuprofen, may beincluded. Also agents which enhance cell activity, such as growthfactors or that inhibit enzymes, such as matrix metalloproteinaseinhibitors, such as tissue inhibitors of metalloproteinase (TIMPS) orzinc chelators could be utilized. As a still further option odortrapping elements such as activated carbon, cyclodextrine, zeolite orthe like may be included in the absorbent layer or as a still furtherlayer above the filter layer.

Whilst some embodiments of the present invention have so far beendescribed in which the transmission layer is formed as a 3D knit layer,e.g., two layers spaced apart by a monofilament layer, it will beappreciated that some embodiments of the present invention are notrestricted to the use of such a material. In some embodiments, as analternative to such a 3D knit material, one or more layers of a widevariety of materials could be utilized. In each case, according toembodiments of the present invention, the openings presented by layersof the transmission layer are wider and wider as one moves away from theside of the dressing which, in use will be located proximate to thewound. In some embodiments, the transmission layer may be provided bymultiple layers of open celled foam. In some embodiments, the foam isreticulated open cell foam. The foam can be hydrophilic or able to wickaqueous based fluids. The pore size in each layer is selected so that inthe foam layer most proximate to the wound side in use the pores have asmallest size. If only one further foam layer is utilized that includespore sizes which are greater than the pore sizes of the first layer.This helps avoid solid particulate being trapped in the lower layerwhich thus helps maintain the lower layer in an open configuration inwhich it is thus able to transmit air throughout the dressing. In someembodiments, two, three, four or more foam layers may be included. Thefoam layers may be integrally formed, for example, by selecting a foamhaving a large pore size and then repeatedly dipping this to a lesserand lesser extent into material which will clog the pores oralternatively, the transmission layer formed by the multiple foam layersmay be provided by laminating different types of foam in a layeredarrangement or by securing such layers of foam in place in a knownmanner.

FIGS. 7A-7D illustrate the use of an embodiment of a TNP wound treatmentsystem being used to treat a wound site on a patient. FIG. 7A shows awound site W being cleaned and prepared for treatment. Here, the healthyskin surrounding the wound site W is preferably cleaned and excess hairremoved or shaved. The wound site W may also be irrigated with sterilesaline solution if necessary. Optionally, a skin protectant may beapplied to the skin surrounding the wound site W. If necessary, a woundpacking material, such as foam or gauze, may be placed in the wound siteW. This may be preferable if the wound site W is a deeper wound.

After the skin surrounding the wound site W has been prepared, the cover151 can be removed from the first packaging element 150 to provideaccess to the components. The dressing 102 can be removed from thepackaging 150 and, as illustrated in FIG. 7B, be positioned and placedover the wound site W. The wound dressing 102 can be placed with thewound contact layer of the dressing 102 over and/or in contact with thewound site W. In some embodiments, an adhesive layer can be provided ona lower surface of the wound contact layer, which may in some cases beprotected by an optional release layer to be removed prior to placementof the wound dressing 102 over the wound site W. The dressing 102 can bepositioned such that the port 108 is in a raised position with respectto the remainder of the dressing 102 so as to avoid fluid pooling aroundthe port 108. In some embodiments, the dressing 102 is positioned sothat the port 108 is not directly overlying the wound, and is level withor at a higher point than the wound. To help ensure adequate sealing forTNP, the edges of the dressing 102 can be smoothed over to avoid creasesor folds. The dressing and the adhesive formed thereon can be configuredsuch that the dressing can be lifted away from the skin or wound andrepositioned to remove creases and folds, or to simply reposition thedressing over the wound, or for other reasons, without sacrificing theperformance of the adhesive. The tubing 106 can be connected to thedressing 102 either before or after placement of the dressing 102 overthe wound.

Thereafter, the pump assembly 104 can be removed from the packaging 150and connected to the tubing 106, as illustrated in FIG. 7C. Thebatteries 142 can be removed from the packaging 150 and installed in thepump assembly 104 either before or after the pump is attached to theconduit 106. The pump assembly 104 can be configured to apply negativepressure to the wound site via the dressing 102, and typically throughthe tubing or conduit 106. In some embodiments, a connector may be usedto join the conduit 106 to the dressing 102 and to the pump assembly104. Upon the application of negative pressure with the pump assembly104, the dressing 102 may in some embodiments partially collapse andpresent a wrinkled appearance as a result of the evacuation of some orall of the air underneath the dressing 102. In some embodiments, thepump assembly 104 may be configured to detect if any leaks are presentin the dressing 102, such as at the interface between the dressing 102and the skin surrounding the wound site W. Should a leak be found, suchleak is preferably remedied prior to continuing treatment. The leak canbe remedied by repositioning the dressing 102, smoothing out wrinkles orfolds in the dressing, or by applying fixation strips 148 around theperiphery of the dressing 102.

Turning to FIG. 7D, as mentioned, fixation strips 148 can be attachedaround the peripheral edges of the dressing 102 or otherwise. Suchfixation strips 148 can be advantageous in some situations so as toprovide additional sealing against the skin of the patient surroundingthe wound site W. For example, the sealing or fixation strips 148 canprovide additional sealing for when a patient is more mobile. In somecases, the fixation strips 148 may be used prior to activation of thepump assembly 104, particularly if the dressing 102 is placed over adifficult to reach or contoured area. In some embodiments, the dressingkit 100 can be provided with up to five sealing strips.

Treatment of the wound site W preferably continues until the wound hasreached a desired level of healing. In some embodiments, it may bedesirable to replace the dressing 102 after a certain time period haselapsed, or if the dressing is full of wound fluids. During suchchanges, the pump assembly 104 may be kept, with just the dressing 102being changed.

FIGS. 8A-20H are top isometric, bottom isometric, top plane, bottomplane, front, back, first side, and second side views, respectively, ofembodiments of packaging elements that can be used with any of theembodiments of the wound dressing apparatuses disclosed herein,including a variety of differently sized wound dressing apparatuses. Anyof the embodiments of the packaging elements illustrated in FIGS. 8A-20Hor otherwise disclosed in this application can have any of the samefeatures, materials, or other details of any of the other packagingelements disclosed herein, including first packaging element 150discussed above.

The packaging element 300 illustrated in FIGS. 8A-8H is configured tosupport a dressing that has an approximate 10 cm×20 cm size, and/or oneor more of the other components of any TNP therapy kits disclosedherein. The packaging element 310 illustrated in FIGS. 9A-9H isconfigured to support a dressing that has an approximate 10 cm×20 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 320 illustrated in FIGS. 10A-10His configured to support a dressing that has an approximate 10 cm×30 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 330 illustrated in FIGS. 11A-11His configured to support a dressing that has an approximate 10 cm×30 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 300 illustrated in FIGS. 12A-12His configured to support a dressing that has an approximate 10 cm×40 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 350 illustrated in FIGS. 13A-13His configured to support a dressing that has an approximate 10 cm×40 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 360 illustrated in FIGS. 14A-14His configured to support a dressing that has an approximate 15 cm×15 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 365 illustrated in FIGS. 14I-14Pis configured to support a dressing that has an approximate 15 cm×15 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein.

The packaging element 370 illustrated in FIGS. 15A-15H is configured tosupport a dressing that has an approximate 15 cm×20 cm size, and/or oneor more of the other components of any TNP therapy kits disclosedherein. The packaging element 380 illustrated in FIGS. 16A-16H isconfigured to support a dressing that has an approximate 15 cm×20 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 390 illustrated in FIGS. 17A-17His configured to support a dressing that has an approximate 20 cm×20 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 395 illustrated in FIGS. 17I-17Pis configured to support a dressing that has an approximate 20 cm×20 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 400 illustrated in FIGS. 18A-18His configured to support a dressing that has an approximate 15 cm×30 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 405 illustrated in FIGS. 18I-18Pis configured to support a dressing that has an approximate 15 cm×30 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 410 illustrated in FIGS. 19A-19His configured to support a dressing that has an approximate 25 cm×25 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein. The packaging element 420 illustrated in FIGS. 20A-20His configured to support a dressing that has an approximate 25 cm×25 cmsize, and/or one or more of the other components of any TNP therapy kitsdisclosed herein.

FIG. 21 illustrates a pump assembly 1000 according to some embodiments.Any of the embodiments of the pump assembly 1000 disclosed herein canhave any of the same or similar components, features, materials, sizes,configurations, and other details of any other pump assembly embodimentsdisclosed or incorporated by reference herein, including the embodimentof the pump assembly 104 described above. Preferably, the pump assembly1000 can be miniaturized and portable, although larger conventionalportable or non-portable (e.g., wall suction) pumps can also be used.The pump assembly 1000 can include a switch or a button 1002,illustrated as a play/pause button located on the exterior of thehousing of the pump assembly. As is explained below, the button 1002 canbe configured to stop, pause, and/or restart therapy. Althoughillustrated as a press button 1002, other types of switches or buttonscan be included, such as a touchpad, touch screen, keyboard, and so on.

The pump assembly can further include a connector 1050 (for connecting aconduit, e.g., conduit 106), and three LED indicators 1062, 1064, and1066. As is illustrated, LED indicator 1062 (e.g., OK indicator) can beconfigured to indicate normal/abnormal operation of the system. Forexample, an active (e.g., lit) indicator 1062 can represent normaloperation. LED indicator 1064 (e.g., dressing indicator) can beconfigured to indicate a leak in the system. For example, an active(e.g., lit) indicator 1064 can represent a leak. LED indicator 1066(e.g., battery indicator) can be configured to indicate the remainingcapacity or life of a power source (e.g., batteries). For example, anactive (e.g., lit) indicator 1066 can represent a low capacity. In someembodiments, the indicators 1062, 1064, and 1066 can be of a differentcolor, two different colors (e.g., two indicators can share the samecolor), or same color. Although the pump assembly preferably includesthree LED indicators and a push play/pause button, other configurations,locations, and types of indicators, alarms, and switches canalternatively be used. In some embodiments, the pump assembly 1000 caninclude visual, audible, tactile, and other types of indicators oralarms configured to signal to the user various operating conditions.Such conditions include system on/off, standby, pause, normal operation,dressing problem, leak, error, and the like. The indicators can includespeakers, displays, light sources, etc., and/or combinations thereof.

FIG. 22 illustrates a cross-sectional view showing the interior of thepump assembly 1000 according to some embodiments. As is illustrated, ahousing 1020 can enclose the pump assembly. A one-way flow valve 1030can be configured to maintain a level of negative pressure when thesource of negative pressure is not active (e.g., prevent leaks) andprevent fluids and/or exudate aspirated or removed from the wound fromentering the pump assembly via the connector 1050. A control board 1040,such as a printed circuit board assembly (PCBA), can be configured tomechanically support and electrically connect variouselectrical/electronic components, which are described below. The PCBAcan be single-sided or double-sided. A negative pressure source 1090,such as pump, can aspirate fluid and/or exudate from a wound. In any ofthe embodiments disclosed herein, the negative pressure source 1090 canhave any of the same components, features, limitations, or other detailsof any of other negative pressure source embodiment disclosed herein,including without limitation the pump 232 disclosed above. Various pumpscan be used for the negative pressure source, including peristalticpumps, piston pumps, rotary vane pumps, liquid ring pumps, scroll pumps,diaphragm pumps, piezoelectric pumps (e.g., a diaphragm pump operated bya piezoelectric transducer), etc. or combinations thereof. Although thepump assembly preferably includes a miniature, low noise, low powerpump, any suitable pump can alternatively be used. The pump assembly1000 includes indicators 1060 (e.g., LEDs), a pressure sensor 1070 formonitoring pressure in the system, such as pressure under the dressing,and a battery cover 1080 configured to provide access to a batterycompartment 1100. Although the pump assembly is preferably powered bytwo standard, disposable alkaline batteries (e.g., 2 AA batteries), anytype of power source, including rechargeable batteries and externalpower, can alternatively be used.

FIG. 23 illustrates a system schematic of the pump assembly 1000according to some embodiments. The pump assembly includes a press button1002, a control board 1040, and indicators 1060. The pump assembly 1000can be powered by a battery cell 1130. The pump assembly also includes apump 1090, such as a diaphragm pump powered by an electric motor 1092,and a pressure sensor 1070. An inlet 1120 can be configured to connectthe pump assembly 1000 to a dressing, for example, via a conduit. Theinlet 1120 can be connected to a one-way valve 1030, which can beconfigured to help maintain a level of negative pressure when the sourceof negative pressure is not active, avoid leaks, and prevent fluidsand/or exudate aspirated or removed from the wound from entering thepump assembly 1000. The pump 1090 can also be connected to an outlet1110. In some embodiments, the outlet 1110 can be configured to vent airto the atmosphere. In some embodiments, a filter (not shown) can beinterposed between the outlet and the atmosphere. The filter can be abacterial filter, odor filter, etc. or any combination thereof.

FIG. 24 illustrates an electrical component schematic of the pumpassembly 1000 according to some embodiments. Module 1140, which can be acontrol board (e.g., PCBA), can include an input/output (I/O) module1150, controller 1160, and memory 1170. In some embodiments, module 1140can include additional electric/electronic components, for example, fuseor fuses. The controller 1160 can be a microcontroller, processor,microprocessor, etc. or any combination thereof. For example, thecontroller 1160 can be of STM8L MCU family type from STMicroelectronics, such as STM8L 151G4U6, or of MC9S08QE4/8 series typefrom Freescale, such as MC9S08QE4CWJ. Preferably, the controller 1160 isa low power or ultra low power device, but other types of devices canalternatively be used. Memory 1170 can include one or more of volatileand/or nonvolatile memory modules, such as one or more of read-onlymemory (ROM), write once read many memory (WORM), random access memory(e.g., SRAM, DRAM, SDRAM, DDR, etc.), solid-state memory, flash memory,magnetic storage, etc. or any combination thereof. Memory 1170 can beconfigured to store program code or instructions (executed by thecontroller), system parameters, operational data, user data, etc. or anycombination thereof.

The I/O module 1150 can be configured to function as an interfacebetween the controller 1160 and other system components that provideand/or are responsive to electromagnetic signals. In other words, theI/O module 1150 can be configured to allow the controller 1160 tomonitor the operation of the system and to control other components ofthe system. In some embodiments, as is illustrated, the I/O module 1150can be in electromagnetic communication with a button 1002, indicators1060, pressure sensor 1070, power source 1130, and source of negativepressure 1090. The I/O module can comprise an interface or multipleinterfaces configured to communicate with various components. Theinterface can include standard and/or non-standard ports, such as serialports, parallel ports, bus interfaces, etc. or any combination thereof.

In some embodiments, the pump assembly 1000 can be configured to controlthe operation of system. For example, the pump assembly 1000 can beconfigured to provide a suitable balance between uninterrupted deliveryof therapy and/or avoidance of inconveniencing the user by, for example,frequently or needlessly pausing or suspending therapy and a desire toconserve power, limit noise and vibration generated by the negativepressure source, etc. FIG. 25 illustrates a top level state diagram 1200of operation of the pump assembly according to some embodiments. In someembodiments, the controller 1140 can be configured to implement the flowof the state diagram 1200. As is illustrated in FIG. 25, the operationof the pump assembly can, in some embodiments, be grouped into fourgeneral state categories: inactive/initialization (states 1206 and1202), active 1210, operational 1250, and end of life (state 1214). Asis illustrated in FIGS. 25 and 26, state categories 1210 and 1250 eachcomprises multiple states and transitions between states.

In some embodiments, so long as the power source is not connected,removed (as is illustrated by the transition 1204), or the pump assemblyhas not been activated (e.g., by pulling an activation strip, triggeringthe switch, or the like), the pump assembly remains in state 1206. Whileremaining in this state, the pump assembly can remain inactive. When thepower source is connected and/or the pump assembly has been activatedfor a first time, the pump assembly transitions to state 1202, wherepower on self test(s) (POST) can be performed. Power on self test(s) caninclude performing various checks to ensure proper functionality of thesystem, such as testing the memory 1170 (e.g., performing a check, suchas a cyclic redundancy check, of the program code to determine itsintegrity, testing the random access memory, etc.), reading the pressuresensor 1070 to determine whether the pressure values are within suitablelimits, reading the remaining capacity or life of the power source(e.g., battery voltage, current, etc.) to determine whether it is withinsuitable limits, testing the negative pressure source, and the like. Asis illustrated, indicators 1060 (e.g., LEDs) can be configured toindicate to the user (e.g., by blinking or flashing once) that the pumpassembly is undergoing POST test(s).

In some embodiments, if one or more of POST test(s) fail, the pumpassembly can transition to non-recoverable error state 1214. While inthis state, the pump assembly can deactivate therapy, and the indicators1060 can be configured and indicate to the user that an error wasencountered. In some embodiments, all indicators can be configured toremain active. Based on the severity of error, in some embodiments, thepump assembly can be configured to recover from the error and continueoperation (or transition to the non-recoverable error state 1214). As isillustrated, the pump assembly can transition to state 1214 uponencountering a fatal error during operation. Fatal errors can includeprogram memory errors, program code errors (e.g., encountering aninvalid variable value), controller operation errors (e.g., watchdogtimer expires without being reset by the controller 1160), componentfailure (e.g., inoperative negative pressure source, inoperativepressure sensor 1070, etc.), and any combination thereof.

When POST test(s) pass, in some embodiments, the pump assembly cantransition to a manually paused state 1216. As is illustrated, thistransition can be indicated to the user by deactivating one ofindicators 1060 (e.g., battery indicator 1066). When the pump assemblytransitions into and remains in the manually paused state 1216, the usercan be provided an indication, such as by deactivating indicators 1062(OK indicator) and 1064 (dressing indicator). In some embodiments,therapy can be suspended while the pump assembly remains in the manuallypaused state 1216. For example, the source of negative pressure (e.g.,pump 1090) can be deactivated (or turned off). In some embodiments,indication can be provided by deactivating the source of negativepressure.

In some embodiments, the pump assembly can be configured to make atransition 1224 from the manually paused state 1216 to the operationalstate category 1250 (where the pump assembly is configured to delivertherapy) in response to receiving a signal from the switch. For example,the user can press a button to start, suspend, and/or restart therapy.In some embodiments, the pump assembly can be configured to monitor theduration of time the pump assembly remains in the manually paused state1216. This can be accomplished, for example, by maintaining a timer (infirmware, software, hardware or any combination thereof), which can bereset and started when the pump assembly transitions into the manuallypaused state 1216. The pump assembly can be configured to automaticallymake the transition 1224 from the manually paused state 1216 to theoperational state category 1250 when the time duration exceeds athreshold. In some embodiments, such threshold can be a preset value,such as between 1 minute or less and 1 hour or more. In someembodiments, the threshold can be set or changed by the user. In someembodiments, the threshold can be varied based on various operatingconditions or on any combination thereof. For example, as the pumpassembly nears the end of life (as is explained below), the thresholdcan be decreased. In some embodiments, the user can pause therapy byactivating the switch (e.g., pressing the button), thereby causing thepump assembly to make a transition 1222 from the operational statecategory 1250 to the manually paused state 1216. In some embodiments,the pump assembly can be configured so that the user can only pausetherapy, whereas disconnecting the power source (e.g., removingbatteries) stops therapy.

In some embodiments, the pump assembly can be configured to include apaused state 1218. When the pump assembly transitions into and remainsin the paused state 1218, the user can be provided an indication. Forexample, the pump assembly can be configured to deactivate the OKindicator 1062 and cause the dressing indicator 1064 to flash or blink.In some embodiments, therapy can be suspended while the pump assemblyremains in the manually paused state 1216. For example, the source ofnegative pressure (e.g., pump 1090) can be deactivated (or turned off),which provides the indication to the user that the pump assembly is inthe paused state 1218. As is explained below, in some embodiments, thepump assembly can be configured to transition from the operational statecategory 1250 into the paused state 1218 when a number of retry cyclesexceeds a retry limit (transition 1228) or when duty cycle is determinedto exceed a duty cycle limit (transition 1230). In some embodiments,transitions 1228 and 1230 can reflect the presence of a leak in thesystem.

In some embodiments, the pump assembly can be configured to make atransition 1226 from the paused state 1218 to the operational statecategory 1250 (where the pump assembly is configured to activate thepump to deliver therapy) in response to receiving a signal from theswitch (e.g., the user pressing a button to restart therapy). In someembodiments, the pump assembly can be configured to monitor the durationof time the pump assembly remains in the paused state 1218. For example,this can be accomplished by maintaining a timer (in firmware, software,hardware or any combination thereof), which can be reset and startedwhen the pump assembly transitions into the paused state 1218. The pumpassembly can be configured to automatically make the transition 1226from the paused state 1218 to the operational state category 1250 whenthe time duration exceeds a threshold. The threshold can be the same ordifferent than the threshold of the manually paused state 1216 describedabove. In some embodiments, the threshold can be a preset value, such asbetween 1 minute or less and 1 hour or more. In some embodiments, thethreshold can be set or changed by the user. In some embodiments, thethreshold can be varied based on various operating conditions or on anycombination thereof. For example, as the pump assembly nears the end oflife (as is explained below), the threshold can be decreased.

In some embodiments, the pump assembly includes both the manually pausedstate 1216 and the paused state 1218 in order to differentiate betweenvarious causes for pausing therapy. Such ability to differentiate canallow the pump assembly to provide the user with an indication of aparticular cause for pausing therapy (e.g., manually paused state 1216and paused state 1218 can provide different indications). For example,therapy can be paused due to the user manually pressing the button, inwhich case the pump assembly can make the transition 1222 from theoperational state category 1250 to the manually paused state 1216. Asanother example, therapy can be paused due to detecting a leak, in whichcase the pump assembly can make the transition 1228 and/or 1230 from theoperational state category 1250 to the paused state 1218. In someembodiments, the pump assembly can be configured to include one stateindicating a suspension or pause in the delivery of therapy or more thantwo such states.

In some embodiments, the pump assembly can be configured to monitor theremaining capacity or life of the power source (e.g., by periodicallyreading or sampling the battery voltage, current, etc.). The pumpassembly can be configured to indicate to the user the remainingcapacity. For example, if the power source is determined to have anormal remaining capacity (e.g., as a result of comparison to athreshold, such as 2.7V, 2.6V, 2.5V, etc.), the battery indicator 1066can be deactivated. If the power source is determined to have lowremaining capacity, the pump assembly can be configured to provide anindication to the user by, for example, causing the battery indicator1066 to blink or flash, as is illustrated by the transition 1220. Insome embodiments, the battery indicator 1066 can be configured to beblinking or flashing intermittently or continuously regardless of thestate the pump assembly is in or only in particular states.

In some embodiments, when the remaining capacity of the power source isdetermined to be at or near a critical level (e.g., as a result ofcomparison to a threshold, such as 2.4V, 2.3V, 2.2V, etc.), the pumpassembly can be configured to transition into a battery critical state1212. In some embodiments, the pump assembly can be configured to remainin this state until the capacity of the power source is increased, suchas by replacing or recharging the power source. The pump assembly can beconfigured to deactivate therapy while remaining in the battery criticalstate 1212. In addition, as is illustrated, the pump assembly can beconfigured to indicate to the user that the power source is at or nearthe critical level by, for example, deactivating all indicators.

In some embodiments, the pump assembly can be configured to providetherapy for a predetermined period of time, such as approximately 1 day,2-10 days, etc. following a first activation. In some embodiments, suchperiod of time can be a preset value, changed by the user, and/or variedbased on various operating conditions or on any combination thereof. Thepump assembly can be disposed upon the expiration of such period oftime. In some embodiments, the first activation can be reflected by atransition into the active state category 1210, by pulling theactivation strip (e.g., transition into state 1202), etc. Once the pumpassembly has been activated, the pump assembly can be configured tomonitor the duration it has remained active. In some embodiments, thepump assembly can be configured to monitor the cumulative duration ofremaining in the active state category 1210. This can be accomplished,for example, by maintaining a timer (in firmware, software, hardware orany combination thereof), that reflects such duration.

When the duration reaches or exceeds a threshold (e.g., 7 days), thepump assembly can be configured to transition to an end of life (EOL)state 1240. The pump assembly can be configured to deactivate therapywhile remaining in state 1240 and to indicate to the user that end ofpump assembly' usable life has been reached. For example, the pumpassembly can be configured to deactivate all indicators and/ordeactivate the button. In some embodiments, when the pump assembly isdisposable, transitioning to the end of life state 1240 means that thepump assembly can be disposed of. The pump assembly can be configured todisable reactivation of the pump assembly once the end of life has beenreached. For example, the pump assembly can be configured to not allowreactivation even if the power source is disconnected and reconnectedlater, which can be accomplished by storing an indication, value, flag,etc. in the read only memory.

FIG. 26 illustrates the operational flow in state category 1250 of thepump assembly 1000 according to some embodiments. The pump assembly canbe configured to deliver therapy, monitor leaks in the system, provideindication(s) to the user, and the like. As is explained below, in someembodiments, the pump assembly can be configured to deliver therapy byinitially attempting to establish a first desired negative pressurelevel (e.g., negative pressure between −5 mmHg or less and −200 mmHg ormore, such as −100 mmHg) under the dressing 1010. In some embodiments,the first desired negative pressure level can be a preset value, set orchanged by the user, and/or varied based on various operating conditionsor on any combination thereof. Once the first desired negative pressurelevel is established under the dressing 1010, the pump assembly can beconfigured to deactivate the source of negative pressure (e.g., pump).When negative pressure under the dressing 1010 decreases (i.e.,gravitates toward standard atmospheric pressure) due to leaks in thesystem, the pump assembly can be configured to restore negative pressureunder the dressing by activating the pump to establish a second desirednegative pressure level under the dressing (e.g., negative pressurebetween −5 mmHg or less and −200 mmHg or more, such as −100 mmHg). Insome embodiments, the second desired negative pressure level can be apreset value, set or changed by the user, and/or varied based on variousoperating conditions or on any combination thereof. In some embodiments,the first and second desired negative pressure levels can be the same.In some embodiments, the first and second desired negative pressurelevels can be different, that is, the second negative pressure level canbe less than the first negative pressure level or vice versa.

In some embodiments, the pump assembly can transition from the manuallypaused state 1216 and/or paused state 1218 to state 1252. As isexplained above, this transition can be caused by the user pressing thebutton to start/restart therapy and/or upon expiration of duration oftime, such as 1 hour. The pump assembly can be configured to immediatelytransition to an initial pump down (IPD) state 1260, where the pump canbe activated to establish the first desired negative pressure levelunder the dressing 1010. In some embodiments, the pump can be activatedif the pressure level under the dressing is above (less than) the firstdesired negative pressure level. Activating the source of negativepressure to establish the first desired negative pressure level underthe dressing 1010 can be referred to herein as the “initial pump down.”The pump assembly can be configured to indicate to the user that it isperforming the initial pump down by, for example, causing the OKindicator 1062 to blink or flash and deactivating the dressing indicator1064. In some embodiments, the indication can be provided by, forexample, activating the source of negative pressure. The pump assemblycan be configured to measure the level of pressure under the dressing1010 by reading or sampling the sensor 1070.

In some embodiments, the pump assembly can be configured to monitor theduration of time the pump assembly remains in the IPD state 1260. Thiscan be accomplished, for example, by maintaining a timer (in firmware,software, hardware or any combination thereof), which can be reset andstarted when the pump assembly transitions into the IPD state 1260. Insome embodiments, in order to conserve power, limit the noise and/orvibration generated by the pump, etc., the pump assembly can beconfigured to suspend the initial pump down operation for a period oftime and, later, retry the initial pump down. This functionality can,for example, conserve battery power and allow transient and/ornon-transient leaks to become resolved without user intervention orallow the user to fix the leak (e.g., straighten the dressing, fix theseal, check the connection or connections, etc.).

In some embodiments, when the duration of time for remaining in the IPDstate 1260 equals or exceeds a threshold (e.g., 30 seconds), the pumpassembly can be configured to make the transition 1264 to state 1266. Insome embodiments, the threshold can be a preset value, such as between 5seconds or lower and 5 minutes or higher. In some embodiments, thethreshold can be set or changed by the user. In some embodiments, thethreshold can be varied based on various operating conditions or on anycombination thereof. In some embodiments, the pump assembly can beconfigured to deactivate the pump when making the transition 1264. Thepump assembly can be configured to monitor a number attempts (e.g., bymaintaining a counter which can be reset in state 1252 and updated inwait state 1270) made to establish the first desired negative pressureunder the dressing 1010. In some embodiments, the pump assembly can beconfigured to provide a limited or maximum number of IPD retry attemptsin order, for example, to conserve power. Preferably, the pump assemblycan be configured to provide a limited number of consecutive IPD retryattempts, although the pump assembly can be configured to provide alimited number of non-consecutive IPD retry attempts or a mix ofconsecutive and non-consecutive IPD retry attempts. The threshold forIPD retry attempts can be 1, 2, 3, 4, 5, and so on. In some embodiments,the threshold can be a preset value. In some embodiments, the thresholdcan be set or changed by the user. In some embodiments, the thresholdcan be varied based on various operating conditions or on anycombination thereof.

In some embodiments, the pump assembly can be configured to determine instate 1266 whether the number of IPD retry attempts made is equal to orexceeds the threshold (e.g., 1 retry attempt). In case the number of IPDretry attempts made is equal or exceeds the threshold, the pump assemblycan be configured to make the transition 1228 a to the paused state1218, where therapy is paused or suspended as is described above.Otherwise, the pump assembly can be configured to make the transition1268 to the wait state 1270. In some embodiments, the pump assembly canbe configured to deactivate the source of negative pressure in state1266, which can provide an indication to the user that the pump assemblytransitioned to state 1266.

In some embodiments, the pump assembly can be configured to deactivatethe pump in the wait state 1270, thereby pausing therapy for a period oftime (e.g., between 1 second or less and 1 minute or more, such as 15seconds). This can be accomplished, for example, by maintaining a timer(in firmware, software, hardware or any combination thereof), which canbe reset and started when the pump assembly transitions into the waitstate 1270. This period of time in the wait state 1270 can be preset orvariable (e.g., automatically or by the user). In some embodiments, theperiod of time can be varied based on various operating conditions or onany combination thereof. The period of time the pump assembly remains inthe wait state 1270 can be decreased or increased (e.g., multiplied by afactor between 0.1 or less and 4.0 or more, such as 2), on eachtransition into the wait state 1270. The period of time can be decreasedor increased on each successive transition into the wait state 1270. Theperiod of time can be decreased or increased until it equals or passes athreshold (e.g., between 1 second or less and 5 minutes or more, such as4 minutes). In addition, the period of time can be reset to an initialvalue upon transition to a monitor pressure state 1280, transition tothe manually paused state 1216, transition to the paused state 1218,etc.

In some embodiments, the pump assembly can be configured to indicate tothe user that the pump assembly is in the wait state 1270. For example,the pump assembly can be configured to cause the OK indicator 1062 toflash or blink and deactivate the dressing indicator 1064. In someembodiments, deactivating the pump can provide indication that the pumpassembly is in the wait state 1270. Upon expiration of the period oftime in the wait state, the pump assembly can be configured to make thetransition 1272 from the wait state 1270 to the IPD state 1260, wherethe pump assembly can attempt to establish the first desired negativepressure level under the dressing 1010. In some embodiments, the pumpassembly can be configured to ensure that the negative pressure levelunder the dressing remains above a certain safety level. For example,the pump assembly can be configured to maintain the negative pressurelevel under the dressing 1010 above a safety level between −150 mmHg orless and −250 mmHg or more, such as −225 mmHg.

In some embodiments, when the first desired negative pressure levelunder the dressing 1010 has been established, the pump assembly can beconfigured to make the transition 1276 to a monitor state 1280. The pumpassembly can be configured to reset the number of IPD retry attemptswhen making the transition 1276. The pump assembly can be configured toindicate the transition to the monitor state 1280 to the user by, forexample, causing the OK indicator 1062 to blink or flash anddeactivating the dressing indicator 1064. While remaining in the monitorstate 1280, the pump assembly can be configured to deactivate the pump(which can provide an indication to the user that the pump assembly isin the monitor state 1280) and periodically or continuously monitor thelevel of pressure under the dressing 1010. The pump assembly can beconfigured to measure the level of pressure under the dressing 1010 byreading or sampling the sensor 1070.

In some embodiments, the pump assembly can be configured to determinewhether, for example, due to leaks in the system, the level of negativepressure under the dressing 1010 decreases to reach and/or pass (e.g.,become less than) a threshold. The threshold can be selected from therange between −10 mmHg or less and −100 mmHg or more, such as −60 mmHg.In some embodiments, the threshold can be a preset value, set or changedby the user, and/or varied based on various operating conditions or onany combination thereof. If the threshold is determined to be reached orpassed, the pump assembly can be configured to restore the level ofnegative pressure under the dressing 1010. In some embodiments, the pumpassembly can be configured to reestablish the first desired negativepressure level or establish another, different negative pressure level.This can be accomplished by making the transition 1282 to a maintenancepump down (MPD) state 1290.

In some embodiments, the pump assembly can be configured to activate thepump to establish the desired level of negative pressure under thedressing 1010 (e.g., the first desired level) while the pump assemblyremains in the MPD state 1290. The pump assembly can be configured toprovide an indication to the user, for example, by causing the OKindicator 1062 to blink or flash and deactivating the dressing indicator1064. In some embodiments, the pump assembly activating the source ofnegative pressure can provide an indication to the user that the pumpassembly transitioned to state 1290. In some embodiments, the pumpassembly can be configured to generate less noise and vibration when thepump is activated in the MPD state 1290 than when the pump is activatedin the IPD state 1264. For example, the difference in the noise levelcan be between 1 dB or less and 30 dB or more, such as approximately 7dB, approximately 20 dB, etc. As another example, the difference in thenoise level can be between 30 dB or less to 80 dB or more, such asapproximately 45 dB, approximately 50 dB, approximately 65 dB, etc.

In some embodiments, the pump assembly can be configured to monitor theduration of time it remains in the MPD state 1290. This can beaccomplished, for example, by maintaining a timer (in firmware,software, hardware or any combination thereof), which can be reset andstarted when the pump assembly makes the transition 1282 into the MPDstate 1290. In some embodiments, in order to conserve power, limit thenoise and/or vibration generated by the pump, etc., the pump assemblycan be configured to suspend the maintenance pump down operation for aperiod of time and, later, retry the initial pump down and/ormaintenance pump down. This functionality can, for example, conservebattery power and allow transient and/or non-transient leaks to becomeresolved without user intervention or allow the user to fix the leak(e.g., straighten the dressing, fix the seal, check the connection orconnections, etc.).

In some embodiments, when the duration of time in the MPD state 1290equals or exceeds a threshold (e.g., a value between 5 seconds or lowerand 5 minutes or higher, such as 10 seconds) and the pressure levelunder the dressing 1010 has not reached the desired negative pressurelevel, the pump assembly can be configured to make the transition 1292to state 1294. The threshold can be a preset value, set or changed bythe user, and/or varied based on various operating conditions or on anycombination thereof. In some embodiments, the pump assembly can beconfigured to deactivate the pump when making the transition 1292, whichcan provide an indication to the user that the pump assembly is makingthe transition. The pump assembly can be configured to monitor a numberof MPD attempts (e.g., by maintaining a counter which can be reset inthe state 1252 and/or when making the transition 1228 b and updated whenmaking the transition 1296) made to establish the desired negativepressure under the dressing 1010. In some embodiments, the pump assemblycan be configured to provide a limited or maximum number of MPD retryattempts (e.g., to conserve power). Preferably, the pump assembly can beconfigured to provide a limited number of consecutive MPD retryattempts, although the pump assembly can be configured to provide alimited number of non-consecutive MPD retry attempts or a mix ofconsecutive and non-consecutive retry attempts. The threshold for MPDretry attempts can be 1, 2, 3, 4, 5, and so on. In some embodiments, thethreshold can be a preset value, set or changed by the user, and/orvaried based on various operating conditions or on any combinationthereof. The pump assembly can be configured to set the number of IPDand MPD retry attempts to the same or different value. The pump assemblycan be configured to determine in state 1294 whether the number of MPDretry attempts made is equal to or exceeds the threshold (e.g., 3 retryattempts). In case the number of MPD retry attempts made is equal orexceeds the threshold, the pump assembly can be configured to make thetransition 1228 b to the paused state 1218, where therapy is paused orsuspended as is described above. Otherwise, the pump assembly can beconfigured to make the transition 1296 to the wait state 1270, wheretherapy is paused or suspended as is described above. Alternatively, thepump assembly can be configured to make the transition to the IPD state1260 or MPD state 1290.

In some embodiments, the pump assembly can be configured to make thetransition 1284 to the monitor state 1280 if the level of pressure underthe dressing reaches or exceeds (e.g., become greater than) the desirednegative pressure level. The pump assembly can also be configured toreset the number of MPD retry attempts when making the transition 1284.

In some embodiments, the pump assembly can be configured to monitor theduty cycle of the source of negative pressure (e.g., pump). The pumpassembly can be configured to monitor the duty cycle periodically and/orcontinuously. Duty cycle measurements can reflect various operatingconditions of the system, such as presence and/or severity of leaks,rate of flow of fluid (e.g., air, liquid and/or solid exudate, etc.)aspirated from wound, and so on. For example, duty cycle measurementscan indicate presence of a high leak, and the pump assembly can beconfigured to indicate this condition and/or temporarily suspend orpause operation of the pump in order to conserve power. Thisfunctionality can, for example, conserve battery power and allowtransient and/or non-transient leaks to become resolved without userintervention or allow the user to fix the leak (e.g., straighten thedressing, fix the seal, check the connection or connections, etc.).

In some embodiments, the pump assembly can be configured to periodicallymonitor the duty cycle, such as once between every 10 seconds or lessand 5 minutes or more. In some embodiments, the pump assembly can beconfigured to monitor the duty cycle once per minute. This can beaccomplished by maintaining a timer (in firmware, software, hardware orany combination thereof), which can be set to expire every minute (e.g.,as is indicated by an interrupt or via polling) and can be restarted(e.g., by clearing an interrupt). In some embodiments, the time intervalfor measuring the duty cycle can be a preset value, set or changed bythe user, and/or varied based on various operating conditions or on anycombination thereof. In some embodiments, the pump assembly can beconfigured to monitor the duty cycle when the pump assembly is in theoperational state category 1250 (i.e., any of states 1260, 1266, 1270,1280, 1290, 1294 and/or any transitions between any of the states), asthe pump assembly is configured to activate the pump in this statecategory. In some embodiments, the pump assembly can be configured tomonitor the duty cycle when the pump assembly is in a particular stateand/or state transition or subset of states and/or state transitions ofthe operational state category 1250. In some embodiments, the pumpassembly can be configured to monitor the duty cycle when the pumpassembly is in a particular state and/or state transition, subset ofstates and/or state transitions, or all states and/or state transitionsof the active state category 1210 or any combination of any statesand/or state transitions disclosed herein. As is illustrated in FIG. 26,the pump assembly can make the transition 1302 from any of states 1260,1266, 1270, 1280, 1290, 1294 and/or transitions between any of thestates to state 1300, where the pump assembly determines the duty cycleof the pump during the elapsed minute. The duty cycle can be determinedaccording to the equation:

DC=t/T,   (2)

where DC is the duty cycle, t is the duration that the source ofnegative pressure is active, and T is the total time underconsideration. In case of monitoring the duty cycle once per minute(i.e., T=60 seconds), the duty cycle can be expressed (e.g., in percent)as:

DC=(Pump run time during the elapsed minute/60)*100%   (3)

In order to determine the duty cycle, the pump assembly can beconfigured to monitor the duration of time that the pump has been active(e.g., the pump run time) and/or inactive.

In some embodiments, the pump assembly can be configured to compare thedetermined duty cycle to a duty cycle threshold, which can be selectedfrom the range between 1% or less and 50% or more. The comparison can,for example, indicate presence of a leak in the system. In other words,if the pump is remains active over a period of time so that the dutycycle threshold is reached or exceeded, the pump may be working hard toovercome the leak. In such cases, the pump assembly can be configured tosuspend or pause the delivery of therapy. The pump assembly can beconfigured to provide an indication to the user that the pump is workinghard (e.g., duty cycle exceeds the duty cycle threshold) by, forexample, deactivating the source of negative pressure. In someembodiments, the duty cycle threshold can be a preset value, set orchanged by the user, and/or varied based on various operating conditionsor on any combination thereof. As is illustrated in FIG. 26, the pumpassembly can be configured to compare the determined duty cycle to theduty cycle threshold (e.g., 9%). The pump assembly can be configured tomonitor the number of duty cycles that exceed the threshold by, forexample, maintaining and updating an overload counter, which can bereset when the pump assembly transitions from state 1252 to the IPDstate 1260.

In some embodiments, the pump assembly can be configured to update theoverload counter in state 1300. If the determined duty cycle does notexceed the duty cycle threshold, the pump assembly can decrement theoverload counter. In some embodiments, the minimum value of overloadcounter can be set to zero, that is the overload counter cannot becomenegative. Conversely, if the determined duty cycle is equal to orexceeds the duty cycle threshold, the pump assembly can increment theoverload counter.

In some embodiments, the pump assembly can be configured to monitor atotal or aggregate number of duty cycles that equal to or exceed theduty cycle threshold. This approach can help to smooth or average theduty cycle variation in order to, for example, prevent one or severalerratic cycles that may be caused by a transient leak from interruptingtherapy. In some embodiments, the pump assembly can be configured tomonitor consecutive or non-consecutive duty cycles exceeding the dutycycle threshold. In some embodiments, the threshold can be a presetvalue, set or changed by the user, and/or varied based on variousoperating conditions or on any combination thereof. If the number ofduty cycles that exceed the duty cycle threshold is determined to exceedan overload threshold (e.g., a number between 1 and 60 or more, such as30), the pump assembly can be configured to make the transition 1230 tothe paused state 1216, where therapy is suspended or paused as isdescribed above. In some embodiments, the pump assembly can beconfigured to deactivate the source of negative pressure, which canprovide an indication to the user that the pump is working hard (e.g.,duty cycle exceeds the overload threshold). If the number of duty cyclesthat exceed the duty cycle threshold is not determined to exceed theoverload threshold, the pump assembly can be configured to make thetransition 1304 and remain in the operational state category 1250. Insome embodiments, the pump assembly can be configured to return to thesame state and/or transition between states from which the pump assemblymade the transition 1302. In some embodiments, the pump assembly can beconfigured to transition to a different state and/or transition betweenstates.

In some embodiments the pump assembly is further configured to suspendor pause therapy if the user presses the button 1002 while the pumpassembly is in the operational state category 1250. In some embodiments,the pump assembly can be configured to transition to the manually pausedstate 1216.

FIG. 27 illustrates another state diagram of operation of the pumpassembly 1000 according to some embodiments. In some embodiments, thecontroller 1140 can be configured to implement the flow of the statediagram 1400. In some embodiments, the flow 1400 can be largely similarto the flow illustrated in FIGS. 25-26. State 1402 corresponds to state1202, state 1406 corresponds to state 1260, state category 1410corresponds to state category 1210, state 1414 corresponds to state1214, state 1416 corresponds to state 1216, state 1418 corresponds tostate 1218, transition 1420 corresponds to transition 1220, transition1422 corresponds to transition 1222, transition 1424 corresponds to thetransition 1224, transition 1426 corresponds to transition 1226, andstate 1440 corresponds to state 1240. In addition, state category 1450corresponds to state category 1250, state 1460 corresponds to state1260, transition 1464 corresponds to transition 1264, state 1466corresponds to transition 1266, transition 1468 corresponds totransition 1268, transition 1428 a corresponds to transition 1228 a,state 1470 corresponds to state 1270, and transition 1472 corresponds totransition 1272. Further, transition 1476 corresponds to transition1276, state 1480 corresponds to state 1280, transition 1482 correspondsto transition 1282, state 1490 corresponds to state 1290, transition1492 corresponds to transition 1292, state 1494 corresponds to state1294, transition 1496 corresponds to transition 1296, and transition1428 b corresponds to transition 1228 b.

In some embodiments, the pump assembly can be configured to monitor theduty cycle after a desired negative pressure level is established underthe dressing 1010 in the MPD state 1490. In some embodiments, the pumpassembly can also take into account the duration of time that the pumphas been active while the pump assembly remains in the IPD state 1460.As is illustrated, the device can be configured to make the transition1484 from the MPD state 1490. Transition 1484 can be similar to thetransition 1284, but instead of transitioning directly to the IPD state1480, the pump assembly can be configured to monitor the duty cycle instate 1500. In some embodiments, the pump assembly can be configured tomonitor the duty cycle during a cumulative period of time that the pumpassembly has remained in the monitor state 1480 and MPD state 1490. Insome embodiments, the pump assembly can be configured to monitor theduty cycle over the cumulative period of time during the immediatelypreceding or previous monitor and MPD cycles. For example, immediatelybefore transitioning to state 1500 the pump assembly could have remainedin the MPD state 1490 for time duration X (during which the pump wasactive). In addition, assuming that immediately before transitioning tothe MPD state 1490, the pump assembly remained in the monitor state 1480for a time duration Y (during which the pump was not active), the dutycycle (DC) can be expressed (e.g., in percent) as:

DC=100%*[X/(X+Y)].   (4)

In order to determine the duty cycle, the pump assembly can beconfigured to monitor the duration of time that the pump has been activeand/or inactive.

In some embodiments, the pump assembly can be configured to compare thedetermined duty cycle to a duty cycle threshold (e.g., 9%), as isdescribed above. In some embodiments, the threshold can be a presetvalue, set or changed by the user, and/or varied based on variousoperating conditions or on any combination thereof. If the duty cycle isdetermined to be below the threshold, the pump assembly can beconfigured to make the transition 1502 to the monitor state 1480.Conversely, if the duty cycle is determined to be equal to or exceed thethreshold, the pump assembly can be configured to make the transition1504 to state 1506. In some embodiments, the pump assembly can providean indication that the duty cycle exceeds the threshold by, for example,deactivating the pump.

In some embodiments, the pump assembly can be configured to monitor atotal or aggregate time over which the duty cycle is equal to or exceedsthe threshold. This approach can help to smooth or average the dutycycle variation in order to, for example, prevent one or several erraticcycles that may be caused by a transient leak from interrupting therapy.Monitoring can be accomplished by maintaining a timer (in firmware,software, hardware or any combination thereof), which can be restarted(e.g., on the transition 1476) and updated (e.g., in state 1506). Insome embodiments, the pump assembly can be configured to determinewhether the duty cycle equals to or exceeds the threshold over a certainaggregate period of time, which can be compared to an aggregate durationthreshold. The threshold can be selected from a range between 5 minutesor less and 2 hours or more, such as 30 minutes. In some embodiments,the threshold can be a preset value, set or changed by the user, and/orvaried based on various operating conditions or on any combinationthereof. If the aggregate period of time equals to or exceeds thethreshold, the pump assembly can be configured to make the transition1508 to the paused state 1418, where the pump assembly can be configuredto suspend or pause the delivery of therapy. In some embodiments, thepump assembly can indicate this transition to the user by, for example,deactivating the pump. Conversely, if the aggregate period of time isdetermined to be less than the threshold, the pump assembly can beconfigured to make the transition 1510 to the monitor state 1480. Thepump assembly can be configured to indicate the transition 1510 to theuser by, for example, causing the OK indicator 1062 to blink or flashand deactivating the dressing indicator 1064.

FIG. 28 illustrates a graph 1600 depicting a duty cycle determinationfor the pump assembly 1000 according to some embodiments. The x-axisrepresents time and the y-axis represents pressure. In some embodiments,the pump assembly can be configured to establish a negative pressurelevel of −100 mmHg under the dressing 1010, as is represented byposition 1606. For example, this can be performed during the initialpump down in state 1260. The pump assembly can be configured to monitorthe level of negative pressure under the dressing 1010. For example,this can be performed in the monitor state 1280. As is illustrated, thepump assembly can monitor pressure over the period of time a, asrepresented by interval 1602. The level of negative pressure under thedressing 1010 can decay over time (e.g., due to leaks in the system), asis illustrated by line 1620.

In some embodiments, the pump assembly can be configured to restore orreestablish the negative pressure level under the dressing 1010 whenthat pressure decays to reach or pass a threshold of approximately −70mmHg, as is represented by position 1608. In some embodiments, the pumpassembly can be configured to activate the pump, as is illustrated byline 1622. For example, this can be performed by transitioning to themaintenance pump down state 1290. As is illustrated, the pump assemblycan activate the pump for a time duration b (1604) until the negativepressure level of −100 mmHg is reestablished under the dressing 1010.The pump assembly can be configured to deactivate the pump when thelevel of pressure under the dressing 1010 reaches −100 mmHg at position1610. For example, this can be performed by transition to the monitorstate 1280. The duty cycle (DC) over the period illustrated in 1600(i.e., a+b) can be expressed (e.g., in percent) as:

DC=100%*[b/(a+b)].   (5)

FIG. 29 illustrates a non-limiting example of a normal (e.g., no leak orlow leak) operation 1700 of some embodiments of the pump assembly 1000.The pump assembly can be configured to establish a desired level ofnegative pressure under the dressing 1010, as is illustrated in box1702. The pump assembly can be configured such that, if the level ofpressure under the dressing 1010 rises above a desired level (e.g.,first set point value, such as −70 mmHg), the source of negativepressure (e.g., a pump) will be activated and will start operating toreduce the level of pressure under the dressing 1010 to the desiredvalue. For example, the desired value can be approximately within theinterval between the first and second set point value or approximatelythe second set point value (e.g., −100 mmHg). In some embodiments, thiscan be accomplished in the initial pump down state 1260.

In some embodiments, when the level of pressure under the dressing 1010reaches the desired value, the pump assembly can be configured todeactivate the pump and monitor the level of pressure under thedressing, as is illustrated in box 1704. For example, this can beaccomplished in the monitor state 1280. The pump assembly can beconfigured to periodically or continuously monitor the level of pressureunder the dressing 1010 by, for example, reading or sampling the sensor1070. Based on the monitored pressure, the pump assembly can determinein box 1706 whether the pump needs to be activated or restarted toreestablish the desired level of negative pressure under the dressing1010. If the monitored pressure is determined to be low (e.g., less thanor less than or equal to the first set point value), the pump assemblycan be configured to activate the pump, as is illustrated in box 1708.For example, this can be accomplished by transitioning to the MPD state1290. Conversely, if the monitored level of pressure is not determinedto be low (e.g., greater than or greater than or equal to the first setpoint value), the pump assembly can be configured to continue monitoringthe level of pressure under the dressing 1010. During this operationalflow, the pump assembly can be configured to indicate to the user thatit is operating normally. As is illustrated in 1060 a, the pump assemblycan activate or cause to blink or flash the OK indicator 1062, which isdepicted as 1062 a. In addition, the pump assembly can deactivate thedressing indicator 1064 and the battery indicator 1066, which aredepicted as 1064 a and 1066 a respectively.

FIG. 30 illustrates a non-limiting example of operation 1800 of someembodiments of the pump assembly 1000 in presence of a high leak. As isdescribed above in connection with FIG. 29, the pump assembly can beconfigured to establish a desired level of negative pressure under thedressing 1010, as is illustrated in box 1802. In some embodiments, whenthe level of pressure under the dressing 1010 reaches the desired value,the pump assembly can be configured to deactivate the pump and monitorthe level of pressure under the dressing, as is illustrated in box 1804.The pump assembly can be configured to periodically or continuouslymonitor the level of pressure under the dressing 1010 by, for example,reading or sampling the sensor 1070. Based on the monitored level ofpressure, the pump assembly can determine whether the pump needs to beactivated or restarted to reestablish the desired level of negativepressure under the dressing 1010. If the monitored level of pressure isdetermined to be low (e.g., less than or less than or equal to the firstset point value), the pump assembly can be configured to activate thepump, as is illustrated in box 1808. Once the desired level of pressurehas been reestablished under the dressing 1010, the pump assembly canrecommence monitoring the level of negative pressure under the dressing(e.g., transition to the monitor state 1280).

In some embodiments, due to presence of a leak or leaks in the system,the pump assembly 1010 can be configured to carry out multiple cycles ofmonitoring and reactivating the pump. During this operational flow, thepump assembly can be configured to indicate to the user that the pumpassembly is operating normally. As is illustrated in 1060 b, the pumpassembly can activate or cause to blink or flash the OK indicator 1062,which is depicted as 1062 b. In addition, the pump assembly candeactivate the dressing indicator 1064 and the battery indicator 1066,which are depicted as 1064 b and 1066 b respectively. The pump assemblycan be configured to continuously or periodically determine whether thepump is pumping too often, as is illustrated in box 1810. As isillustrated, in some embodiments, the pump assembly can be configured touse the duty cycle as a proxy for determining whether the pump ispumping too often. For example, the pump assembly can be configured todetermine whether the pump is “working hard,” that is determine whetherthe pump is on for more than a threshold duration, such as 9% of thetotal therapy time. In other words, the pump assembly can be configuredto determine whether the duty cycle of the pump reaches or exceeds theduty cycle threshold.

In some embodiments, the pump assembly can be configured to suspend orpause operation of the pump if the pump is determined to be working hardover a duration of time (e.g., the pump is on for more than about 2hours a day, or is on for more than a predetermined amount of time),even if the desired level of negative pressure (e.g., second set pointvalue) has been established. As is illustrated in box 1812, the pumpassembly can be configured to determine whether the pump is working hardfor a duration of 30 minutes or more. For example, the pump assembly canbe configured to determine whether duty cycle (or cycles) monitored overthe past 30 minutes exceed the duty cycle threshold. For example, thepump assembly can determine whether the pump has been on for about 2minutes and 42 seconds or longer over the last 30 minutes, whichcorresponds to 9% duty cycle threshold.

In some embodiments, the pump assembly can be configured to pause orsuspend therapy if the pump is determined to be working hard, as isillustrated in box 1814. The pump assembly can be further configured toturn a “Leak alarm” indicator on. As is illustrated in 1060 c, the pumpassembly can activate or cause to blink or flash the dressing indicator1064, which is depicted as 1064 b, and deactivate the OK indicator 1062and the battery indicator 1066, which are depicted as 1062 c and 1066 crespectively. To restart the therapy, the user may need to straightenthe dressing, to fix the leak, and/or to activate the pump once again.In some embodiments, the pump can be activated again by pressing thestart or operating button on the pump, because of a timeout, etc.

In the case of a leak or leaks being present in the dressing, in someembodiments, the pump assembly 1000 can be programmed or otherwiseconfigured to suspend or pause therapy if the second set point value isnot reached after a predetermined amount of operating time of the pump.For example, in some embodiments, if the pump has been runningcontinuously for X minutes and the second set point pressure value hasnot been reached, the pump assembly can activate an alarm which cancomprise an LED indicator, a “leak detected” LED indicator 1064, orother alarm, and pause the therapy. In some embodiments, thepredetermined amount of time can be approximately 5% of the totalplanned duration of the negative pressure therapy for the system, orfrom approximately 3% or less to approximately 15% or more of the totalplanned duration of the negative pressure therapy for the system. Insome embodiments, the predetermined amount of time can be approximately9 minutes, or from approximately 4 minutes or less to approximately 40minutes or more, or from approximately 6 minutes to approximately 10minutes.

FIG. 31 illustrates a non-limiting example of operation 1900 of someembodiments of the pump assembly 1000 in presence of a very high leak.As is described above in connection with FIG. 29, the pump assembly canbe configured to establish a desired level of negative pressure underthe dressing 1010, as is illustrated in box 1902. In some embodiments,when the level of pressure under the dressing 1010 reaches the desiredvalue, the pump assembly can be configured to deactivate the pump andmonitor the level of pressure under the dressing, as is illustrated inbox 1904. The pump assembly can be configured to periodically orcontinuously monitor the level of pressure under the dressing 1010 by,for example, reading or sampling the sensor 1070. Based on the monitoredlevel of pressure, the pump assembly can determine whether the pumpneeds to be activated or restarted to reestablish the desired level ofnegative pressure under the dressing 1010. If the monitored level ofpressure is determined to be low (e.g., less than or less than or equalto the first set point value), the pump assembly can be configured toactivate the pump, as is illustrated in box 1908. During thisoperational flow, the pump assembly can be configured to indicate to theuser that the pump assembly is operating normally. As is illustrated in1060 d, the pump assembly can activate or cause to blink or flash the OKindicator 1062, which is depicted as 1062 d. In addition, the pumpassembly can deactivate the dressing indicator 1064 and the batteryindicator 1066, which are depicted as 1064 d and 1066 d respectively.

In some embodiments, due to a leak or leaks (e.g., a leak that has arelatively very high flow rate), the pump assembly may not be able toreach a desired negative pressure level and/or the second set pointvalue under the dressing 1010. If after a predetermined amount ofoperating time, the desired negative pressure level is not reached underthe dressing, the pump assembly can be configured to suspend or pausethe pump, as is illustrated in box 1914. For example, this can beaccomplished by transitioning to the wait state 1270. In someembodiments, the predetermined amount of pump operating time can be 10seconds (as is illustrated in FIG. 31). In some embodiments, thepredetermined amount of pump operating time can be from approximately 5seconds or less to approximately 60 seconds or more.

In some embodiments, the pump assembly can be configured to provide alimited number of retry cycles before pausing or suspending therapy. Asillustrated in boxes 1920, 1922, and 1924, the pump assembly can beconfigured to go through three retry cycles before suspending or pausingtherapy (1914) and/or activating an alarm, such as the “Leak alarm.”Some embodiments of the pump assembly can go through two retry cycles,four retry cycles, etc. before pausing therapy and/or activating analarm. As is illustrated in 1060 e, the pump assembly can activate orcause to blink or flash the dressing indicator 1064, which is depictedas 1064 e, and deactivate the OK indicator 1062 and the batteryindicator 1066, which are depicted as 1062 e and 1066 e respectively.

FIG. 32 illustrates a non-limiting example of operation 2000 of someembodiments of the pump assembly 1000 in presence of an extremely highleak. The pump assembly can be configured to quickly go into a therapypause or suspend mode to avoid wasting the batteries trying to cope witha high flow rate leak. As is illustrated in box 2001, the pump assemblycan be turned on, which can be accomplished, for example, bytransitioning into the operational state category 1250. As is describedabove in connection with FIG. 29, the pump assembly can be configured toestablish a desired level of negative pressure under the dressing 1010,as is illustrated in box 2002.

In some embodiments, if the leak is extremely high, such as when thepump is turned on but not yet connected to the dressing or not properlyconnected to the dressing, the pump assembly can be configured tooperate for a predetermined amount of time while attempting to draw thepressure under the dressing 1010 to a desired negative pressure level.(e.g., approximately the second set point value or a value within theinterval between the first and second set point values). The pumpassembly can be configured to suspend or pause therapy upon expirationof the predetermined amount of time. For example, this can beaccomplished by transitioning to the wait state 1270. As is illustrated,the pump assembly can be configured to operate the pump for 30 seconds.If during this period of time the pressure under the dressing 1010 hasnot been drawn to the desired negative pressure, the pump assembly cango into a timeout mode 2020 for another predetermined amount of time(e.g., for 15 seconds, as illustrated in FIG. 32). During thisoperational flow, the pump assembly can be configured to indicate to theuser that the pump assembly is operating normally. As is illustrated in1060 f, the pump assembly can activate or cause to blink or flash the OKindicator 1062, which is depicted as 1062 f. In addition, the pumpassembly can deactivate the dressing indicator 1064 and the batteryindicator 1066, which are depicted as 1064 f and 1066 f respectively.

In some embodiments, the pump assembly can be configured to provide alimited number of retry cycles for establishing the desired level ofnegative pressure under the dressing 1010. As is illustrated, after thefirst trial (or any number of additional trials), the pump assembly canbe configured to establish or reestablish the desired negative pressurelevel under the dressing, as is illustrated in box 2002. In someembodiments, as is illustrated in box 2014, if the pump assemblyoperates for another predetermined amount of time without drawing thepressure under the dressing 1010 to the desired level (e.g.,approximately the second set point value or to a value within theinterval between the first and second set point values) after a firstattempt, the pump assembly can be configured to suspend or pause therapywithout retrying the pump down. The pump assembly can be configured toremain in the suspended or paused state until the pump assembly isreactivated (e.g., due to a timeout, due to the user pressing thebutton, etc.) The pump assembly can be configured to activate an alarmin this state. During this operational flow, the pump assembly can beconfigured to indicate to the user that a leak or leaks are present. Asis illustrated in 1060 g, the pump assembly can activate or cause toblink or flash the dressing indicator 1064, which is depicted as 1064 g,and deactivate the OK indicator 1062 and the battery indicator 1066,which are depicted as 1062 g and 1066 g respectively.

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of the words, for example“comprising” and “comprises”, mean “including but not limited to”, andis they are not intended to (and does not) exclude other moieties,additives, components, integers or steps.

Throughout the description and claims of this specification, thesingular encompasses the plural unless the context otherwise requires.In particular, where the indefinite article is used, the specificationis to be understood as contemplating plurality as well as singularity,unless the context requires otherwise. Further, in some embodiments, theterm approximately is meant to refer to values within 10% of the statedvalues, unless otherwise stated herein.

Any value of a threshold, limit, duration, timeout, retry count, etc.provided herein is not intended to be absolute and, thereby, can beapproximate. In addition, any threshold, limit, duration, timeout, retrycount, etc. provided herein can be fixed or varied either automaticallyor by the user. Furthermore, as is used herein relative terminology suchas exceeds, greater than, less than, etc. in relation to a referencevalue is intended to also encompass being equal to the reference value.For example, exceeding a reference value that is positive can encompassbeing equal to or greater than the reference value.

Features, integers, characteristics, compounds, chemical moieties orgroups described in conjunction with a particular aspect, embodiment, orexample are to be understood to be applicable to any other aspect,embodiment or example described herein unless incompatible therewith.All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive. The protection is not restricted to the detailsof any foregoing embodiments. The protection extends to any novel one,or any novel combination, of the features disclosed in thisspecification (including any accompanying claims, abstract anddrawings), or to any novel one, or any novel combination, of the stepsof any method or process so disclosed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of protection. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made. Those skilled in the art willappreciate that in some embodiments, the actual steps taken in theprocesses illustrated and/or disclosed may differ from those shown inthe figures. Depending on the embodiment, certain of the steps describedabove may be removed, others may be added. Accordingly, the scope of thepresent disclosure is intended to be defined only by reference to theappended claims. The accompanying claims and their equivalents areintended to cover such forms or modifications as would fall within thescope and spirit of the protection. For example, the various componentsillustrated in the figures may be implemented as software and/orfirmware on a processor, controller, ASIC, FPGA, and/or dedicatedhardware. Furthermore, the features and attributes of the specificembodiments disclosed above may be combined in different ways to formadditional embodiments, all of which fall within the scope of thepresent disclosure. Although the present disclosure provides certainpreferred embodiments and applications, other embodiments that areapparent to those of ordinary skill in the art, including embodimentswhich do not provide all of the features and advantages set forthherein, are also within the scope of this disclosure. Accordingly, thescope of the present disclosure is intended to be defined only byreference to the appended claims.

1.-21. (canceled)
 22. A wound therapy apparatus comprising: a pressuresource configured to provide negative pressure to a wound; and acontroller programmed to: activate the pressure source responsive toexpiration of a first period of time from a first deactivation of thepressure source, deactivate the pressure source to cause a seconddeactivation of the pressure source responsive to the pressure sourceattempting and failing to establish a threshold pressure at the wound,and activate the pressure source responsive to expiration of a secondperiod of time from the second deactivation, the second period of timebeing different from the first period of time.
 23. The wound therapyapparatus of claim 22, wherein the second period of time is longer thanthe first period of time.
 24. The wound therapy apparatus of claim 22,wherein the controller is programmed to set the second period of time.25. The wound therapy apparatus of claim 24, wherein the controller isprogrammed to determine the second period of time from a count of anumber of times that the controller deactivated the pressure sourceresponsive to the pressure source attempting and failing to establishthe threshold pressure at the wound.
 26. The wound therapy apparatus ofclaim 22, wherein the controller is programmed to deactivate thepressure source to cause the first deactivation of the pressure sourceresponsive to the pressure source attempting and failing to establishthe threshold pressure at the wound.
 27. The wound therapy apparatus ofclaim 22, wherein the first period of time is between 1 second and 1minute.
 28. The wound therapy apparatus of claim 22, wherein the firstperiod of time is set by a user.
 29. The wound therapy apparatus ofclaim 22, wherein the controller is programmed to detect that thepressure source attempted and failed to establish the threshold pressureat the wound from a failure of a pressure level at the wound to reachthe threshold pressure within a third period of time during which thepressure source is providing negative pressure to the wound.
 30. Thewound therapy apparatus of claim 29, wherein the third period of time isbetween 5 seconds and 5 minutes.
 31. The wound therapy apparatus ofclaim 22, wherein the controller is programmed to detect that thepressure source attempted and failed to establish the threshold pressureat the wound from a level of activity of the pressure source.
 32. Thewound therapy apparatus of claim 22, wherein the controller isprogrammed to detect that the pressure source attempted and failed toestablish the threshold pressure at the wound from a duty cycle of thepressure source.
 33. The wound therapy apparatus of claim 22, whereinthe controller is programmed to detect that the pressure sourceattempted and failed to establish the threshold pressure at the woundfrom a flow rate in a fluid flow path connecting the pressure source andthe wound.
 34. The wound therapy apparatus of claim 22, furthercomprising a sensor configured to detect a pressure level in a fluidflow path connecting the pressure source and the wound.
 35. The woundtherapy apparatus of claim 22, further comprising a wound dressingconfigured to be placed on the wound.
 36. A method of operating a woundtherapy apparatus, the method comprising: activating, by a controller, apressure source to provide negative pressure to a wound upon expirationof a first period of time from a first deactivation of the pressuresource; determining that a threshold pressure at the wound has not beengenerated with the pressure source; deactivating, by the controller, thepressure source to cause a second deactivation of the pressure source inresponse to determining that the threshold pressure at the wound has notbeen generated with the pressure source; and activating, by thecontroller, the pressure source upon expiration of a second period oftime from the second deactivation, the second period of time beingdifferent from the first period of time.
 37. The method of claim 36,wherein the second period of time is longer than the first period oftime.
 38. The method of claim 36, further comprising, by the controller,setting the second period of time according to a count of a number oftimes that the controller deactivated the pressure source due to thethreshold pressure at the wound having not been generated with thepressure source.
 39. The method of claim 36, further comprisingdeactivating, by the controller, the pressure source to cause the firstdeactivation.
 40. The method of claim 36, further comprising determininga level of activity of the pressure source or a duty cycle of thepressure source, wherein the threshold pressure at the wound isdetermined, from the level of activity or the duty cycle, to have notbeen generated with the pressure source.
 41. The method of claim 36,further comprising detecting a pressure level in a fluid flow pathconnecting the pressure source and the wound, wherein the thresholdpressure at the wound is determined, from the pressure level, to havenot been generated with the pressure source.